I’ve read and seen many places that you should stay away from watches with hacking seconds because it’s really bad for the watch movement. Is there any merit to this or is it bs?
This is totally safe as well. It's even mentioned in some watch manuals.This is in contrast to "back hacking" a non-hacking watch to try to stop the seconds hand. As this can make the watch run in reverse, probably not a great thing to do.
You could put it on at precisely the time it's stopped at.If it's designed to hack it's going to hack when you pull the crown to set the time.