Having gone from the F52 to the Studio 2 I can speak from first hand experience.
While the F52 is an overachiever, the Studio 2 is much more transparent and provides a superior sound stage as others have said. The only speaker I've heard that is as detailed as the Studio 2, without any added harshness, is the Quad ESL 63. The upper midrange and treble of the Studio 2 is something special. The F52 isn't really warmer as such, it just isn't as transparent. This does take some of the edge off bright electronics/recordings, but it is a distortion.
I've seen comments over the years that the Ultima 2 series can be a little forward. I don't go along with that. Once I found the optimal room placement and treated my room to eliminate slap echo and sidewall reflections, well I've never heard anything like them. They do strings like no box speaker I've ever heard.
The upstream electronics are obviously a consideration, but the thing that really did it for me was to research room acoustics and determine exactly where to place the Revel's. AND where to place the listening chair. They need to be placed well away from back and side walls to image properly. My old room was 14' wide. My new room is 17'. The difference in imaging was astounding.
If you have a large room, say 400 sq ft or more, I'd go with the Salon 2. My room is 357 sq ft and the Studio 2's more than get the job done. Bring a beefy amp in either case.