Personally, when I have leaves that do that I like to leave them until I can actually twist them off right where they connect at the main stem. The leaf should easily come off if it's okay to do it that way. As you said, the less stress you give at this point the better, since you can still end up with hermies if they get too stressed while in the clone stage... and cutting them may cause unnecessary stress.

If they're that brown already at this point, then they'll likely just fall off on thier own as well - never hurts to just let them do thier thing.