I took the Spree there in 2013 and it was still fantastic. I love that part of the world because the big ocean is right on the other side of the island, and it's damn deep on all sides, so big fish and mammals are frequently seen. We dived 98% on the ocean side, where no one else goes, specifically researching coral health, but made a few dives on the inside looking at the walls. Our protocols required we start the dive on coral in 9 meters or less. The coral does not come that shallow in the inside.
Anyway, San Salvador was one of the healthiest places we saw, along with South Caicos and French Cay. I can't tell you about Riding Rock, and I stayed at the club med in 1998, and although I dove, I wasn't there for the diving. (wink wink) I know a couple of dive instructors from back in the day, one is a park ranger at Dry Tortugas.
Hope I helped. Now that the new boat is on the way, stopping by the mechanic for some <gulp> expensive engine work, I hope to spend a summer there some day in the not too distant future.