Wow, thanks for the replies, much appreciated! I'm coming off an iPhone 5s, so having the latest stuff isn't super important to me (though the s10e is a treat to use after such an old phone). I just don't want a problem I have to deal with when my phone is working great and has no issues right now. And I saw my 5s get slower and slower with each iOS version. In short, I value speed over additional features and want my phone to stay as snappy as possible. I guess my strategy, if I'm allowed to wait, would be to get ver. 9 security patches until they stop and then by that time ver. 10 will be utterly ironed out and I will accept any speed penalties at that time.
The update "version" is listed as: G970U1UEU2BSIP which is totally meaningless to me, but when I look it up it does seem to be a ver. 9 update, so I think I am safe to install it. I just wanted to be sure because with iOS at least, you could not go back once you press the button.