For what it is worth, I recently replaced my Salon I's with the Spires. Each has its strengths and weaknesses. I believe the Spires are more transparent, more extended at the top end, clearer-sounding, and image and soundstage better than the Salons. The Spires are also surprisingly competitive in the bass. The Spires' bass is tighter; the Salons more abundant in the mid-bass region. One difference that might matter is the sweet spot. The Spire sweet spot is much narrower than the Salons. For 2-channel listening, I think the Spire is a 1-person speaker. I would add that the narrow sweet spot of the Spire is more rewarding than the wider sweet spot of the Salon for a single person. For multi-channel, the center channel helps even things out. I do not think the ML Stage is the equal of Revel's Voice, but it is decent enough that I don't cry for my old Revel system. Overall, I am very pleased with the Spire.
My room is about 25x16.
The F52 is a relatively recent introduction by Revel vis-a-vis the Salon I. Perhaps the F52 matched or even surpassed the Salon I by the end of the Salon I's product life. I have never heard the F52.
