For me the two big ones (pun intended in one case
1. Frame lock relief on outside, especially right at edge of clip as it catches loose material of pocket. I had to two hand release my paysan the other day as the pocket material bunched up in the notch. Same has happened on my swayback. I realize it would take more milling with the paysan with it being integral, but these are the things that would make the knife live up to its potential along with figuring out the lock stick. Never had this issue with my CRKs, Spartans, etc...
2. The obsession with XL'ing (yes I verbed that) every model. Enough already.
Cheers
Erik