Absolutely. And I wasn't ignoring what you said about proper form and technique
. So many just don't want to get that learning proper form and technique and heavy weights are MUTUALLY exclusive so I like to beat that dead horse a lot so it sinks in. Also I there is simply a tendancy for people to think that the PS and the shrug are the same thing except for the PS you "cheat". But they really are two different things and your shoulders popping out are what's bound to happen with this haphazard approach, like we both said.
Now I think for the most lifters they will get plenty of strength in the traps without power shrugs or shrugs and usually the upper traps are so strong and dominant to start with you are not going to need a lot of specific shrugging type work. What I like about the power shrug though is that it has some carry over to deads and such.
The only carry over regular shrugs will have to deads is if your upper traps are really unusually weak so that you can't keep the deadlifthing weight under control with the shoulders. I hate it when people say shrugs help with the "lockout" as if locking out a dead involves a shrug. The only way shrugs really help is when weak traps are a limiting factor in general and this is not going to be the case too often.
I think I've read Madcow's points about it before. He also correctly warns about using light weights (relatively speaking).