Mark, at what point would you deem it alright for a trainee to train with the round-back style of deadlift? At the intermediate stage? Or perhaps only if the trainee's primary goals lie with powerlifting?
I guess this begs the question: is it "useful" for a lifter to train the deadlift with a round back if that lifter is only strength training to improve his performance in basketball/soccer/football/hockey/rowing/tennis/whateverthefuckothersport? Or would it be more beneficial in these cases to train with the back in proper extension?