I think LEM is off base. The problem likely has to do with System 7.5, not the IIcx. Notice that they say the IIci wouldn't boot with the driver installed either, and considering my IIci is fully graphics accelerated in 24-bit colour under System 7.1, that is definitely false. I can't guarantee you the 8*24*GC would work with the IIcx, accelerated or otherwise, but I don't see any reason why it wouldn't work in 24 bit mode or any other colour depth as long as you don't go past 7.1. The 8*24 should also be just fine. Those other cards are pretty pricey and I don't think a IIcx would make the most of them, especially in A/UX.

olePigeon, you should definitely do so. It's really quite nice. Wonder how the Mac would have gone if it had proceeded from A/UX instead of NeXTStep.