Agreed, great machines and easy enough to work on. good to know about LCD replacement, should it ever need to be done. I have an SSK4. I do doubled-up rolls of 120 on a single reel. I tape the rolls together end-to-end. I don't use the film clips as mine didn't come with any. The rotation goes more in one direction than the other, so if you orient the reels so the face away from the direction of most rotation, that seems to help. Mine rotates mostly clockwise when viewed from the tank end of the machine, I believe. So I have the entry of the reels pointing away from that direction. (e.g. if entry point on reel is at 12 oclock, the opening points left when looking at the machine from the tank end.) That will tend to not push the film off the reel if it encounters resistance. Good tip about the vinyl blinds though! might try that just to be safe.
on the SSK-4 at least, any of the chemistry can be run through the "save" function. I only do it for C41 bleach, and use the others one-shot.
I use mine with flat vertical 5L containers/bottles I got from Walmart. I use polyethelene tubing I found at the hardware store. Works great, stays cleaner than the vinyl tubing that others use. (Teflon would be even better but more $ and not as easy to find). I use zip-ties to clamp the tube ends onto the valve body, though they are a snug enough fit that it doesn't seem to be required really.
I use 5 gal water bottle for supply and a 5 gal bucket for waste also. I can run about 3 runs (12 rolls) of C-41 before the bucket fills.