A 7100/80 is sweet. 40Mhz system bus and updated ROMS that address the Nubus bug. The 8100/80 was the only other Nubus PPC to have a 40Mhz Bus, but that had the buggy ROMs.I just finished maxing out a 7100 80 with a 400mHz g3 and 128 meg of ram. It is running 7.6.1 :b&w: . It is very fast compared to the old 601 processor. I remember this unit when it first came out in 92 what a computer! I bought this one in the late 1996 used it a few years and then i banished it to the barn. I then liberated it and upgraded it. this project has been very fun. So If you like a machine make run fast otherwise I would agree with the other posts find a nice 8600 etc. and make it run faster. [] ]'>
The 9150 also had a 40Mhz bus in the 120Mhz version, but for some unknown reason, it isn't compatible with G3 PDS upgrades.
A 7100/66 is a bit slower 33Mhz with v1.0 of the ROMs. Still it's a great machine if you don't intend to use high bandwidth Nubus Cards (e.g. VideoVision).
The 6100 is likewise sweet. It can take more RAM than the 7100, up to 264 MB, but the SIMMs are hard to find.
The 8100 I'm not too fond of. I have an 8100/100 that became an 8100/110 through a board swap but that's been through three power supplies. Plus it has only a 33 Mhz Bus (the 110 has a 37Mhz Bus).
It's big, bulky and really dificult to open up. I did manage to bring out the SCSI-2 Internal Bus (to connect external hotswappable SCA80 drives), routing it through one of the Nubus slots. At its peak, it had a SpigotProAV, and external audio connectors (from the CD sound in terminals on the motherboard) and did well converting video from Analog.