Just tried PBRFE10, (I have Hard Disk Manager Suite 2009):
Backup is a little slow, (Best Compression), I suspect this is because it's trying to compress already compressed files, (png, MPEG4, etc), on the partition I tried.
Verified by doing the same backup without compression - it did it in less than half the time.
Unfortunately there's nowhere where you can filter files to not compress.
Backup file mounted and unmounted without a problem but even if you can't, you can browse through the contents within PBRFE10 and export files to another drive.
Restore from within XP went without a hitch and was approx. 30%-40% faster than the, (Best Compression), backup operation.
So I created a Recovery Media on a spare Flash drive and booted from that and was pleasantly surprised when all my HDDs were listed, (AMD 780G with SATA in AHCI mode), something Acronis usually failed to do without having to find the latest filters. A restore using the previously created uncompressed image took 1 minute longer than it did creating it under XP, (6.5 minutes).
Having an extension *.pfm is pretty much a non-event AFAIAC because that's what 'Open With' is for, (there are other extensions which clash, eg. *.nfo, you only have to go to The File Extension Source
and pick a letter).
The extension PFM is also used by:
PFM Printer Font Metrics (Adobe Systems Incorporated)
PFM Portable Float Map Graphics Data
The docs say it mounts as FAT32 but for a 20 or 40 GB image I imagine that's no problem.
The drive information on my mounted backup shows it as NTFS. I don't see how or why they would bother with an on-the-fly NTFS->FAT32 conversion just for working with a mounted image.