I'm pretty sure if you had zero, we could figure that out with your non reply...
I had a G19 and G34 and sold them as I'm moving back to the .40
G23 for now with a G35 coming in the future.
Just checked again, still zero
2 a glock 19 that I love,
and a glock 35 that keeps me wanting a glock 34.
I am a glock Fan boy through and through but I would really recommend skipping the the 21 in favor of an XD45 in a full size or ( tactical) I love glock but as far as I'm concerned the XD is more comfortable then the glock 21 in ,45 and holds more bullets. Perhaps somebody here has both and might let you shoot them prior to purchasing.
I agree, the G21 is too large for my hands, I am hoping the Small Frame is more comfortable, but I did hold a XD and it felt perfect.
Be cautious I have heard tale, and seen three examples of the Mag catch on the 21SF failing, on the tension spring just fell out.
Just do not get the ambi release in the SF and you will be fine. Mine had to go back to Glock and have a non ambi release frame sent to me.