ST old chars are strictly better than S2 chars: they recover one frame faster from hits and blocked attacks.
The big 5 in ST are also viable characters in Hyper.
Shogatsu won tournaments with ST O.Honda and CE Claw.
ST (hyper) and ST (original) are the same in several instances.
The game is extremely funny outside the US, since people won’t always pick CE Dictator, CE Guile, WW Guile and CE/ST old Sagat. It’s too unbalanced.