I think the S90 was actually a pretty popular classical alto mouthpiece in the past, especially among Selmer artists, and still has fans despite the fact that many new mouthpieces have been introduced in the last 10-15 years. I believe that Nathan Nabb formerly used the S90, but now he uses the D'Addario Reserve D155, which he helped develop. Timothy McAllister also used to play the S90 (now he plays Vandoren?). Steven Banks, a young classical player, is another guy who switched from the S90 to the D'Addario Reserve. He even had sound samples from each mp on his website while he was gathering input from listeners. (Banks still plays the S90 on tenor and baritone.)Not many I would have thought.
The brings up a general problem for the OP (also see my post above). Murphy used a Vandoren Optimum for a long time. OP, lots of players jump from mouthpiece to mouthpiece over the course of their careers. Unless you have really solid information about the equipment used during a recording, or you have a video in which you can clearly identify by sight the type of mp being used, it can be difficult to gather the kind of comparative data you're looking for.Otis Murphy was on an S90 the last time I saw him play.
From what I understand, Londeix probably used the S90, but Delangle probably not. Delangle is currently on his new signature Delangle model from Selmer; before that, it was the Selmer Concept; before that, it was the Vandoren Optimum AL3; before that, it was the Vandoren V5.How about Delangle, Londeix, Helmke, etc., the French school?