To be frank I have no personal experience of an A4000 and any of its graphic cards, 4mb just sounds too little to me. When I had BVision it had 8mb and it could run out of graphics mem when I played some game etc. This particular Cybervision must run out memory pretty quickly if you eg. have a nice background pic on your WB and handle some graphics with it at the same time. But zorro III in itself must be quite fast.
4MB actually isn't bad, as long as you don't get too carried away with the resolution - 1280x1024x16 on an '060 already gets pretty slow, 1024x768x16 is about ideal IMHO. I run fairly decent sized backdrops, and things still remain zippy. If you run out of VRAM, swapping over the Zorro bus slows things down a bit but isn't too terrible (esp on Z3). I can't think of any games that would stress a CV64 or PIV whatsoever (obviously a different story with PPC and B/CVision).
PIV and CV64 also have the benefit of awesome auto-switching scandoubler action. But yeah, for sheer performance, high resolutions, etc, I'm sure PCI blows the old Zorro boards away. It's also much easier and cheaper to replace a broken VooDoo or Radeon than a PIV...
