Sounds like a great timer. I'd be interested.
I'm trying to think of processing sequences that I do in the dark that it might not be able to handle, but I can't think of any offhand.
The most complicated, I suppose, might be tray or tank/hanger development where I've got multiple development times. I want to insert the first sheets in at the beginning of development, the next group after a few minutes, and then a third group a few minutes later, and I want an agitation beep every 15 sec, auto advance to the rinse for say 30 sec., and then to the fix for 3 min with an agitation beep every 1 min. If I understand the specs correctly, I could do that.
I suppose the wash sequence could be its own program, if I wanted to do something like a standing wash sequence with an exchange of water at 1 min, 3 min, 7 min, 12 min, 20 min, and 30 min.
And it would be good to be able to run two or more processes at once, so I could wash and start processing the next batch at the same time. I don't know if you've got that option. Different beeps for different processes.
When I use daylight tanks, I use stainless, so I guess I could attach the probe to the outside of the tank with a couple of rubber bands. The cord would have to be long and flexible enough to allow for inversion, and durable enough that it wouldn't crack easily with fatigue over time, and that there would be a simple repair option that the user could accomplish with ordinarily available materials in case RH Designs isn't around when it becomes an issue. If the tank drips, it's also important that chemicals can't drip down the cord and short out the plug.