I'm using an A4000 with CSPPC 604e at 233Mhz. The Radeon card looks really great but to use one I would also need a Mediator PCI 4000Di daughterboard replacement shown here.........
http://amigakit.leamancomputing.com/catalog/product_info.php?cPath=35&products_id=517
But I think it safe to assume that OS4.1 would support cards like the Picasso IV and Cybervision 64/3D which are supported with my current OS4.0 Classic 
:drink:
welll...
I think that AmigaOS4.1 classic was only for ppl that have already a suitable hw to run it...
If you have to buy a 250 card to run it...well...for a bit more you can get a
really better/faster Sam440 used board...