So best I can tell:
1. Improved the safety / no more bruising
2. Made the handguard plastic / making it lighter
3. Made the grip better
4. AR-style mag releases / making the old mags incompatible
5. Sights redesigned for better cowitness
As a guy with two old scorpions and a bunch of old scorpion mags... literally the only thing here valuable to me is the better pistol grip. Which is fine but nothing terribly different than the yetiwurks I chose for my two older models. So yeah, definitely not interesting at all, especially at this price point of 1.3k. Just think of it this way... if you buy the older scorpion at 800 and then put in 500 into after market upgrades? It is WAY better what you end up with getting this thing for 1.3k.
1.3k into an S1 and you have good safeties, better trigger (CZC level even), good grips, better charging handle, good mag release, etc etc. Only if you care about AR-centric mag releases (and really, how many prioritize that?!?) or if you REALLY want to minimize weight is this something worth pursuing. Which I'm guessing CZ will find out is quite the minority.