I used to run a 3302 and did 4 color process on it. The only real issue with that press doing 4 color work is the registration by pushing the sheet rather than pulling the sheet. I did plenty of pleasing 4 color work on it. Registration is pretty good dot for dot as long as you know what you are doing and set it up correctly. One thing you want to make sure is to have a densitometer and run color bars to industry standard ink densities. Or even better, have the press profiled, so you know exactly what they should be. Also great for knowing your dot gain too (VERY IMPORTANT). As for the QM press I don't recommend it. A friend of mine has one who runs a trade shop and it is good for spot color jobs, but he showed me several jobs he just couldn't get to register when he tried 4 color jobs, your could flip throught it and see the mis-registration. My opinion is the Ryobi is better at sheet to sheet registration. Think about it, the Ryobi has a register board, the sheet comes down it, stops, is pushed into registration, and then fed into the press. Same way with a multilith and some hamadas. I also used to run 4-color jobs on a multilith 1250LWCD press with a kompac unit with and with out a t-head with great results. And by the way, all the old presses ran 4 color with pull guides before the invent of the push guide (an older harris is a good example). Hope this helps.
John