Thanks Ratte - I think with your points I've now got enough to warrant an update.
Fake 3.5 Rom eh? You could well be correct, I honestly can't remember what I based the roms in the 'hacked' ...ird.gz's on. ( I thought it was the original shape.rom images - memory )
As you say the main change was pirus 44.1 ( which I found faster & more stable under Amithlon than 3.9's exec... ) Also, it has powerWindowsNG support built in for those who use that. ( me )
Did you find anything else? Can't remember what I did - too long ago.
S3VirgeDX too? Yes, why not? I have a feeling there is native rather than framebuffer support for this card built in to Amithlon if you use CGX drivers!
( again that could be my dodgy memory talking )
I've not heard about 'other' gfx cards but it wouldn't suprise me. If a card has a native P96 or CGX driver, then in theory it should be possible to 'hack' that for Amithlon - well beyond me TBH.