I don't think that 3# per inch is stacking at all. In fact, I'd venture to say that is pretty close to what most hunting weight bows pull before the magic stacking point. On the f-d curves pay attention to the amount of weight at the beginning of the draw cycle. Bows with more preload or weight in the beginning may not feel as smooth to you (I prefer that feel).
There are other things to consider, though, that you can't get from a f-d curve. Finger pinch is very subjective and only the individual can determine that for his/herself. Grip is another thing that needs to be felt firsthand, IMO. Anyway, I won't go into the other hundred things that point to testing as your question was about the pull (sorry for getting off track). But yeah, 3# per inch is pretty good...Mike