I've tried all, I think, of the common brands of straplocks. I've found that if they have a nut or a bolt fixing, it will eventually come loose and a tragedy may happen. I've been a bit lucky but there were one or two close calls.
Dunlop Straplocks have no nuts or bolts - they use a circlip concept that is much more difficult to defeat. I have no problems with them so far and I've been using them for about 12 years.
G.