I will confess, I didn't actually know what the difference was between the S1 and the PS22, so thanks for clarifying (you know, I always wondered what the difference was...). That said (sorry, can't resist mounting a defense for my case, even if it's pretty feeble(:=)), the website says:
"Ideal for audio restoration, sound effects, guitar leads, and more, the PS22 is unsurpassed for Mono to Stereo emulation, enhancing individual tracks, and rebalancing the spatial imaging of stereo mixes."
The last use mentioned in the quote is what I was referring to. Generally a plugin that REQUIRES a mono source will get instantiated on a mono audio track (or aux track), which it will then convert into a stereo track. The fact that you can instantiate it on a stereo track to begin with means that it is sometimes used on stereo material.
BUT... you're right, it's definitely not the tool to use for the panning purposes we've been discussing. And I'm glad to know that it's primary use is mono-to-stereo conversion.
PL