Looking at 10mm Glock ?

[SDGlock23]

Full 10mm runs 200gr @1325 fps.

True, but I could run a 200gr near 1250 fps from the G35 which does compare to the 10mm, maybe not identical to a max 10mm load, that wasn't my point, but comparable and in the same ballpark for sure.

I have a G20SF and a G29SF. Are Gen 4s out for the 10s yet? If so, does their replaceable back-straps make the SF designs obsolete? I would think so. I am interested in the Gen 4 models.

I also like the G30S model. Wish Glock would make a 10mm version

Yes Gen4 model 10mm's have been out for a little while now. I owned a Gen4 20 and I saw a Gen4 29 last time I was at the gun store, I prefer them to the Gen3 SF models, I had those too. I'm sure GunBroker has a few.