I agree on both points. I don't think I'd trust it not to work free of the tripod socket, and I wonder what that kind of continuous stress would do to the socket. Unscrewing aside, I don't think I'd like the camera rotating around like that either.
They way I do it, I feel I have some control, as my 35mm is flat against my side or hip. Even with the lens sticking out, at least I know where it is pointing and can compensate accordingly.
I wasn't sure about the slider - I thought it would just pull the strap up. Watching some youtube videos, though, it seems there is enough friction against the body for the connector to slide.