Actually, the B&W has a well-deserved reputation for being... quirky. Perhaps not as quirky as the Beige G3, but the system's inflicted with a number of design and firmware peculiarities that in some circumstances make it less reliable or "well-baked" than the later "Post-Jobs" Macs. Off the top of my head:
1: As noted, two major motherboard versions, the difference being the accessory UDMA/33 IDE controller that was slapped on to distinguish the system from the Beige G3. The early version suffers data corruption issues.
2: Firewire is an accessory module. It's not uncommon for it to go bad, causing the system to mysteriously die.
3: Reliability, performance, and compatibility are all NOT strong points of the PCI implementation.
4. The B&W is fanatically picky about memory modules, and incompatible modules usually don't fail memory tests. Instead they just randomly crash your system and corrupt your hard disk. (speaking from experience.)
5: They're just plain... finicky. There's a number of people on this board and others who can attest how they'll just fall into these comotose states sometimes and then magically feel better after being left unplugged overnight, things like that.
I would certainly second/third/whatever the theory that the only reason they appear "desirable" at all again is because they're finally starting to get rare. They were *dirt* common not long ago, and the most insidious B&W in that regard was its evil silver cousin, the "Yikes" PCI video G4. Many a person was burned thinking they were getting a Sawtooth for a steal off eBay only to have it turn out to be one of those boat anchors. Undoubtedly given enough time there will be someone out there who's crazy enough to want one on purpose to fill a hole in their collection...