We use them with waterbased mostly some solvent on wheels over powdercoat primer, the liners go on for ages just keep topping them up. Every so often I do change the top when it gets manky every couple of months..
The gun gets contaminated with paint in the same way, it's just the entry point is a quick change system. Maybe you are thinking about the threads for the cup? I used to remove the cup and clean all the threads out before. That's one job saved as now I leave the adaptor in place (having used a bit of gas grade PTFE tape when fitting the adaptor) and flush through well with thinners. The quick fit system doesn't get messed up with paint only a bit in the bore of the adaptor, which is smooth. As for the rest of the gun, your cleaning regime will be the same, what you won't have to do is clean out the cup or its lid.
