With regards to PC comparisons, I'll offer that I can run DOOM fine (and DOOM II playably) on a 50MHz 386DX, but a large part of that is the 256KB onboard cache, high clock speed, and the fact that I have a pretty zippy video card (by ISA standards, anyway.) Even that doesn't cut it for true 3D - Descent is a slideshow even with low quality settings. I'm not 100% sure how video bandwidth compares to an A4000. Certainly the CPU side of things depends largely on what, if any, accelerator you're using - the 4000's stock 68030 only runs at 25MHz, any 030 only has a very small cache and there's no extra cache on the motherboard, and IIRC the onboard fast RAM isn't that fast. Even a decent 68030 accelerator can improve on clock and RAM speed at least (don't know if there's any 3000/4000 accelerators with L2 cache.)
