"Just bought yesterday at the Paris Apple Expo an "Encore/MDX G4 Duet" for my G4 MDD (Mirror Drive Doors) FW800 Dual 1.25GHz. But have a problem - before installing the card I must update the ROM using the ROM Updater from Sonnet and I simply cannot do this because I receive the following message:

(Sonnet Firmware Updater Error Message)

! Unrecognized ROM

Boot Section 0x36173D0B
Recovery Section 0x5252A0C3
Main Section 0xD9EB7B0B

My MDD is showing a "not usual" ROM version. Apple system profiler reports) Bootrom version: 4.6.0f1.
I have just written to Sonnet in hope to receive some help but maybe some readers had the same problem. Thanks for attention.
-Jo"

From the error message the firmware patcher expects a different firmware version - I checked their product page and it didn't mention any specific MDD models were excluded. I then checked Sonnet's support site for the latest version of the firmware patcher (one patcher for all their upgrades apparently) - the current Encore Firmware Updater Installer there is version 3.1(June 8, 2007). I asked if he was using the same version (assuming the one he has came on CD with the upgrade.) - he later said yes (v3.1 included on CD.)
I searched the "Rate your CPU Upgrade" database for MDD owner reports on this Sonnet (7447A IIRC) upgrade but none on that combo to date. Hopefully Sonnet Support will reply soon but if anyone else has seen this or not let me know.
Update: Here's a combination of later mails from Jo, the last on Oct. 4th, Jo wrote it looks like he's not going to be able to use the Sonnet upgrade:

"(were there ever any updates to your MDD's firmware from apple?)
It's possible because they replaced both mother board and processor card two years ago

(maybe their patcher doesn't support the FW800 model?)
I'm waiting for an answer from Sonnet

(he later wrote)
I'm speaking with the Sonnet support and after having tested everything in the process of installation...
they begin to think I've a very rare case of 1 bit error in my ROM. If they confirm that, they will rebuild a new rom for me ....

(On Oct. 4th he wrote)
Here is the end of my adventure...
I won't be able to install the MDX card in my G4MDD :(
Look at the mail I received from Sonnet
-Jo

Subject: ENCORE/MDX G4 DUET 1,8 GHz installation problem
Jo, My engineer Henry got back to me with:

I looked at it yesterday, it is quite bizarre. It looks to me like a modified ROM. The interesting thing is, it is a very subtle addition - it looks like an extra Apple ethernet driver was added. It is added with great skill - nothing our competitors could do. But the ROM version and date of the ROM matches my golden ROM for 4.60f1. There is no way that Apple released two versions with the same date and version number. I think that someone at Apple must have added the extra driver on for some reason, or maybe some very clever hacker.

I could take the driver out, and just make it a golden ROM, but there are two dangers:
1) The ethernet would not longer work
2) the machine may never boot again.

I'm definitely not going to make a special set of patches for this hacked ROM. Customer may want to return his card.

So if you want Henry to make the modifications, let me know and I'll tell him to do it. Or just contact Sonnet France for a refund. You can use our emails as proof something is amiss. They shouldn't give you any grief about a refund. Definitely a special circumstance here."

I wrote Jo to confirm he never updated the firmware or patched it (he did mention the motherboard may have been replaced by apple in the past). I remember some GigaDesign MDD upgrades that didn't work in some MDD models (they were 745x upgrades, not 7447A's though - no firmware patches required for 7455 CPUs.)
Personally considering the cost, rather than spend $600 or so on a dual 1.8GHz 7447A I'd see what the MDD would bring if sold + the $600 - you may get a later/faster mac (used or refurb) for the same price or just a little more. Other options are what some readers have done in the past - find an OEM Apple Dual 1.42GHz upgrade (and copper heatsink). I'd prefer that over a 7447A personally. (no L3 cache with the 7447A, only 512KB L2 onchip - and no firmware patches reqd with the 7455 CPUs)
The systems page, G4 macs section has past articles on the MDD heatsink swap, Dual 1.42GHz OEM CPU module swap, etc. (and some reports in the Rate Your CPU Upgrade database on that also - search for Apple as CPU brand and MDD as mac model)

" I found a great freeware for a bootable Backup-Clone of your Bootcamp-Partition. Works with Windows XP and Vista. The partition has to be NTFS-formated. The best: It works from within Mac OS X - all you need is space for the clone-image. I save mine on an external Firewire-Storage. If you kill your Windows: No need to install the system, updates, tools and programs - just clone your working backup. Imaging-Tools like Norton Ghost or TrueImage are a nogo on Intel-Macs, cause these do not work with EFI (clones won?t boot) - but Winclone does! (and it's free)
http://www.twocanoes.com/winclone/

Features
- Clone Windows XP or Windows Vista with ease.
- Clone to your Bootcamp partition either on a separate drive or on the same that contains your Mac OS X partition.
- Creates image documents that can be stored on any media and double-clicked to open in WinClone.
- Verbose logging so you know what is going on
- Built on the open source ntfstools, which are included in Winclone, so you don't have to install anything else.
- Fast: Restore a 10 GB image in less than 10 minutes.
- Create a Bootcamp partition from within Winclone.
- Do it all from the boot drive: You don't need to boot from a Firewire drive to clone the Windows partition.
- Clean and uncomplicated interface

Best wishes,
macmercy from Germany"

I've also added this to the previous page of Bootcamp user reports/tips. An older report here (9/18/2006) noted using Ghost 9 (not free) to backup an XP partition (but it doesn't run in OS X of course, and not sure about vista compat. or what the current version of ghost is - his post said Ghost 10 didn't work?) I think there were some comments also on using superduper, but that's not free either.
(BTW - Apple recently updated their doc When does Boot Camp Beta expire?.)

DVD+R/RW + DVD-R/RW Drives:
• IDE Samsung "Super Writemaster" (18x) in G5 Tower (OS X 10.4.x)
  (has lightscribe support also)
• IDE Pioneer DVR-112D in G5 Tower (OS X 10.4.x)
  
  Hard Drives:
• IDE SerialATA onboard Samsung HM250JI (Firmware HS100-08) 250GB in MacBook (OS X 10.4.x)
  (Some earlier reports noted problems with this drive. the Aug 8th news had a Guide to Firmware Update/Fix for Samsung HM250JI 250GB Notebook HD Issues)

You can find full owner reports (latest shown first) by searching the database by drive/brand/interface/mac models (the latest reports are shown first in searches). The database includes reports on DVD +/-R, CDRWs, Combo DVD-CDRW, DVD-ROM, Hard Drives and Removables (tape drive, ORB, ZIP, MO drives, NAS, CF/Smartmedia readers, etc.) in all interface types (IDE, IDE RAID cards, SATA, Firewire, SCSI, USB, adapters).
If you've added a IDE, SATA, Firewire, USB, or SCSI, hard drive, Optical drive/burner, NAS (including Airport Extreme base connected USB drive), tape drive, etc., send me the details (drive info/mac model/OS used, etc. - *Please take a minute to test for booting from CD with Optical drives*. Thanks.)

• Netscape Navigator 9.0rc1
• Second Life 1.18.3.5
• iDefrag 1.6.2
• Cinema 4D 10.5
• OpenOffice.org 2.3
• MacFamilyTree 5 public beta
• Firmware updates for Intel-based Macs require a GUID partition scheme (Apple)
• About firmware updates for Intel-based Macs (Apple)
• iMac (Mid 2007): About new startup tones (Apple)
• iTunes Wi-Fi Music Store FAQ (Apple)
• (Apple) Quick Tip of the Week: Perfect pastes every time
• Review of Netgear Smart Switches
• New DxO Optics Pro v5 Has Breakthrough RAW Engine
• iPhone's Bluetooth bug under the hacker microscope
• Altered iPhones freeze up (ref: 1.1.1 update)
• New York resident files quixotic suit over iPhone price cut
• When does Boot Camp Beta expire? (Apple)
• Logic Pro/Express 8: How the EXS24 sampler addresses RAM in Logic 8 (Apple)
• Adobe Flash Player 9.0.64 (beta)
• X-Plane 8.61rc1
• Adium X 1.1.3 (Multi-protocol IM client)
• iShowU 1.47 (Capture anything on your screen as a movie)
• Movie Conversion Tools 1.0.1 (free collection of four drag-and-drop converters)
• Gimp.app 2.4rc3
• Keyspan USB Adapter X 2.4 (drivers)
• Nvidia ForceWare Release 163.71 for Win XP (FYI for bootcamp users)