Based on favorite model polls here and the Spyderco forum, activity on IG, FB etc., I would estimate that the PM2 outsells the Para 3 by about 3:1.
The Para 3 tip would naturally be slightly stronger than the PM2, simply because it's the exact same geometry as the PM2, just shortened.
The PM2 and Para 3 don't really feel similar at all to me. The PM2 is one of my favorite folders, but I can't get a full four finger grip on the Para 3 without using the choil, and the blade feels way too short. It doesn't seem like much, but I find myself constantly wishing for the extra bit of blade and the more acute tip of the PM2.
I think that both the Native and Delica are superior 3" models, with profiles that are more properly scaled to their blade length. The Para 3 is a 4" design that's been massaged into a 3.5" version and then later shoehorned into a 3" model. It completely abandons any pretext of feeling or performing like a Millie. Both the Native and Delica were conceived as 3" folders, and the difference is very apparent.