The BR lugs don't 'lock' but there's a rubber compression washer that produces reverse tension to prevent unscrewing. Irrelevant in my case, with Loctite into the 1" QR clamp.
I meant that a heavy lens is a lot of weight on your neck, better to put it on your shoulder, ergonomically. Not worried about either attachment point, both are plenty strong. Also, I'd rather have the camera hanging by the hip, not in front of my chest.
The BosStrap looks nice, but how would I attach it to a lens foot? Regardless of strength, with a lens heavy enough that Canon provides a tripod collar, I'd rather suspend the combo by that collar, at the center of mass, vs. by the camera.
As for concerns over security, I hang ~12 lbs of gear, costing ~$20K, from a BR strap (1D X + 600/4L IS II). I trust it.