Ok, maybe I'll ask GM to make 1-12" the standard twist. The 1-10" seems to do no harm, but perhaps it does no good in comparison to the 1-12" either.

And a faster twist does generate a bit more recoil all other things being equal.

The 9.3X57 was an issue in the back of my mind. Of the common 9.3s still made it's the slowest one, so I was thinking that 1-12" may not be perfect from the 57 Mauser case. If you are getting MOA from a 9.3X57 with long heavy bullet it seems obvious that 1-12" is going to do fine. The 62, 64 and 74 are all faster.
I am learning something here.