I use one of those leader retriever thingies to pull the leader out of the cassette so I can trim it straight and cut the tip off the corners with the lights on, before I turn the lights off and pry the end off for loading into a developing tank. I think the maximum distance that the metal blades can reach is about one time around the film at the outside of the spool, and almost all 35mm cameras lose more than this getting to the first frame. So unless a lab uses a much longer retriever (can't imagine why they would - the leader is at the end of the film, and you only have to grab an inch or two to pull it out of the light trap) there shouldn't be much risk of scratching a worthwhile frame.(posted 8882 days ago)Of course, this is only theory, and a man with experience beats a man with a theory almost every time (please, no gender neutrality flames on this.) I do B&W almost exclusively, so have virtually no experience with labs, but I will say that the half dozen color negative rolls I take in a year don't seem to get scratched by the camera store lab that I use.
Cheers, Kip Babington