A bit of history. Only part of it has been addressed here so far.
Rotary processors were of two basic types. The "external tube" machines were like the Jobo, the Sidekick, the Wing Lynch, and the early monster I used to print on, the 30k and it's even more monstrous Kodak cousins. It made 30x40s in a drum which spun rapidly, and had no temperature control. Worked great, but you had to keep the room reasonably warm. The tube was a poor thermal conductor, however, which tended to keep the temperatures inside constant.
The internal tube machines had heated cabinets. Inside, the drums rotated in temperature controlled darkness. There were a bunch of these, but most were replaced with the external drum machines, which could be more easily automated. The Merz was one of these internal tube devices. It was a really great system. I could process anything in it; type C, Cibachrome or whatever else up to 20x24, any kind of film 35mm to 16x20, even 70mm. Some of these machines had water baths that kept the chemicals at the right temp, and then you'd pour them in and the tempered cabinet would keep them at the same.
I'm sure there is a lot of the internal drum stuff lying around unused. I almost NEVER hear of internal drum machines anymore, but I think if you are interested in rotary processing, it would be a viable option if you could find one. We used to make precision quality dupes which we then ganged for reproduction with the Merz. It is capable of very high quality and consistent work. The other machines, mostly, weren't as slick, but they can work just fine. You just have to pour the chemicals yourself -- unless you happen to come by one of the Merz's control modules. Well, you don't have room for that. They were huge.