I think the advantage of a true two stage trigger is that it is safer due the the increased sear engagement prior to taking up the first stage. The pseudo two stage triggers are basically set on a knife edge to give a creep free 'second' stage. I also think that with heavier triggers its more difficult to gradually squeeze the shot off as due to the weight of pull it takes more time to release the shot which means holding aim for longer. I find it much easier with a light trigger but they can be too light.