I fitted some very simple Valiant ones to the last little Humber - Nylon webbing with a decent quality s/s foot-plate and two large diametre, short self tappers, bedded on Sikaflex, which grabbed the webbing well.
They have been tested!
Just a thought on position though: mine were set so that I could "stand" knees bent in a "shock absorbing" stance!!
From horseriding, the most balanced position is with your shoulder/hip/heel all lined up.
Having said all that, I believe there is a school of though that suggests straps may be dangerous - if you do get hurled about they can apparently cause muscle / tendon tears? Probably preferable, in most circumstances, to MOB though?