"Cons are that you don't have a DA alternative on the first shot, and if you fire and get a "fail to fire", you need to cock it (partially rack the slide) for it to fire again. "
--- As far as the cons go, I don't think that not having full DA is a detriment. I much prefer the lighter, shorter QA for the first shot. As far as failure to fire problems, it is true that with guns without exposed hammers like the Glock or Walther P99 QA, you can't just pull the hammer back and refire, however, one, I'm not sure that I want to waste time restriking a round that has failed to fire. I'd rather eject it and get to the next round. You can rack the slide about 1/4" without ejecting the round and have it recock. I have only tried this with snap caps so I don't know if it would work with a real round, though I don't see why not.
The travel of the trigger for the QA is similar to a Glock. It doesn't have the rapid refire of a glock.