to be perfectly honest, I must say that I may have never seen (or recognised) an S1 or an S2 model 🙁
Mainly there are the Bs,
LTD Y1 (spoked wheels, chain) and
LTD K1 (cast wheels, BeltDrive) present in Germany.
Some M/CSRs, at least two Y2, one G model known, but no S model at all.
That’s a list from my own, more than 15 years of experience in the german Z750Twin community.
OK, let’s get a LTD K1 and swap the belt with a chain and we’ve got a close to S2 😉 (As far as I understand :-)))