I have a Quadra 700 and running A/UX I was getting regular disk checks on start up after a clean shutdown with a Quantum Fireball 3.2Gb disk.

I swapped it for a smaller disk and came to the conclusion that the Quadra was cutting the power before the Fireball had completed it's queued/delayed writes. Eg, the mac thought the data was written, the disk hadn't actually completed the writes.

Otherwise I'm a minimalist, original spec, max ram, decent disk, network if it needs it, that's it.