So, it seems like I've done a naughty thing: I bought another vintage PowerBook. This time it's a Duo 2300c.
A downside of 30-year-old Mac is the trackball is sometimes finicky and has proven resilient to my efforts. I've actually thought about acquiring a Wombat ADB-USB bridge so that I can use a modern mouse^ with my Duo 230. Later models tended to retain some serious hardware compatibility and reuse but eventually replaced the trackball with a standard trackpad.
I've thought about acquiring a junked late model Duo for parts or trying to find piece meal parts of the old upgrade kits to refit my Duo 230 with a trackpad. Given the age of parts, probably better off with the Wombat approach. Encountering a 2300c in good shape that doesn't cost more than a decent modern laptop of course was too tempting a target.
In my tastes for PowerBooks, things tend to lean more in the direction of subnotebook and ultra-portables. Even today, the Duo series greatly reflects my tastes in computing. 20-year-old-Mac's PowerPC processor has been kind of nifty since it can emulate Motorola 68k and run native PPC code. But the 'Street series is too damned hefty for my tastes even if its G3 blazes compared to an old '30.
Interchangeability of parts between the Duo 200 series seems to be pretty high, but I'm not sure how true that is with the 2300c for internals. But unlike other PowerPC models I'd care for, because it's the last Duo: it's compatible with my peripherals. By contrast, other options lead in the direction of proprietary model-specific gear. The 2300c has the same dock port as the earlier Duo 200 series.
Depending on what shape its internals are in, I might end up with two functioning machines or kit bashing them together. I've been more interested in the 68k / system 7 era, but I can't say that I really mind prospects of a 603e at nearly triple the clockrate of my 68030.
^ While I'm sure Apple must have made a decent ADB mouse at some point, I can't say that I enjoy the rolling ball mice of old as much as I do an actual track ball or an optical based mouse.