I briefly owned a manix but, on the model I received, I found the lock awkward to disengage as well as being way too stiff. Granted it probably would have broken in after a while, and I know a lot of people love the lock. That was just my experience.
As for the PM2, my only complaint (and most people would see this as a positive) is how crazy smooth it is. It's super fun to flick, but when I try to do a slower, controlled opening it's SO smooth that breaking the detent basically sends the blade flying out! Like I said, most people search for a crazy smooth knife. However, I think a knife can be smooth without being SO smooth. I actually like a smooth opening knife that also has some resistance. I know that seems like two contradictory things but I don't think it is.
As always, this is all just my opinion.