(1) A vast difference in a gain of a sense of dimmension and fluidity. I wouldn't be without one - I think I could skip a tube pre-amp, or any pre-amp at all before I'd lose a tube amp. (In fact in one system I have now done just that!)
I'll pass on 2) and 3) as I have no knowledge the Rogues and there are just too many possibilities for 3) and the right one depends on many things personal to your specific needs, including budget, flexibility, and features.
I'll pass on 2) and 3) as I have no knowledge the Rogues and there are just too many possibilities for 3) and the right one depends on many things personal to your specific needs, including budget, flexibility, and features.