Let me clarify what I think angel_freak is trying to say.
The way that the barrels attach "blow" as he puts it.
They are different then traditional threaded, it's a clamping style barrel system. So if you want a non lapco/site mfg/pps barrel you have to have it shaved down (any barrel can have this done to it and it is cheap to have done.)
So it isn't contradictory. That should solve your where his opinion comes from, unless you mean the accuracy...but i've never seen anyone that doesn't like blazer accuracy.