I see absolutely ZERO benefit to doing this yet see multiple injury possibilities, do you also do 1 armed barbell curls as well? Don't know who you thought you were trying to impress with this!
There's no sense in doing them with a barbell. They are a great movement with dumbbells especially for people who's knees tend to collapse inwards when they squat being up on one leg forces you to use stabilizing muscles that aren't normally hit during a traditional squat. I like to do them right after a normal squat workout when you are already taxed.
No way I'd d that but that is a hell of a lift good work. I just wonder where you go with that back leg if you fail? I'd think you would snap a leg or ankle.