Thanks. I do have a Watson but have yet to use it. However from my brief examination of it, it seems that once the top hinge has been closed and the gate can then be opened the film runs through more or less straight without touching anything so my assumption is that the Watson has less chance of scratching than some other loaders where the film moves around corners on its way out.
I have plastic re-useable cassettes which have ends that screw on quite tight and have never had an end unscrew. Maybe I have been lucky