You really can't go wrong with the larger machine if you have the space for it. Problem with these big machines is that, well, they are big and heavy. If installing in a spot where you won't have to move it, great. They're built like tanks and will take all the punishment you can dish out and more. They were designed to dependably endure hard commercial use day in and day out. If this is going into a "temporary" darkroom (read blacked out bathroom) that's going to be a problem. How would you like to lug around and set up a machine that weighs easily 50 pounds or more and is around 4 feet tall every time you want to print? Not me. I have a 4x5 Omega D4. The thing is a beast. It just barely clears the ceiling in my darkroom, but I don't have to move it. I'll never be able to wear it out in my lifetime.