According to some veteran folks in the CN boards, if using an APS-C camera Bin2 should still be plenty of resolution so there should not be any penalty effect on polar alignment. And it would allow for quicker steps to fine tune/correct the offsets. However, in PA mode Bin1 is set and greyed out, so it cannot be changed.
I found one older thread about this here: https://bbs.zwoastro.com/d/15964-change-from-bin-2-for-polar-aligning
Apparently in older versions Bin2 was default but this was changed to Bin1. The thread is suggesting that the same Bin as in Preview mode is used (if I understand it correctly), but if I change it to Bin2 it will not have any effect on the Bin setting in PA mode - also, I have not found any other menu option that lets me change it.
So is this indeed fixed and there is no way to change, or am I missing something?