Peacekeeper is average at best, even at very close range. At anything more than super close, it becomes extremely bad against any legend that is not the fatty Gribraltar.
I really can't remember the last time I 2-shotted a wraith, even when I was right in her face (blue+ armor ofc). I've done single-mag kills plenty of times with R99. I would even rather have an R301 in CQC than PK.
PK is somewhat equal to R99 vs Gribraltar, but R99 wins out very decisively against any of the smaller legends. So does any AR, for that matter.
If you can't down some1 with 1 mag of AR/SMG, then you most definitely won't 2-shot anyone with PK either.
P.S. The choke is kind of just for trolling (or when you don't have any alternatives) - you're not going to win any mid-long range fights with that long charge time.
If peacekeeper got any more nerfs, it would go down a tier and would only compete with the likes of alternator, which would be a pity. A game where end-game weapons were all fast-firing full-auto weapons would be extremely dull and boring. It's nice to have variety, even if the best weapons are still the SMG's.
P.P.S. I wonder, what are the ppl who say that PK is OP are playing? I would guess they main 1 of the fatties (gribraltar, pathfinder, caustic). In those cases, the AR's/SMG's are as good as PK against them, but ppl that have trouble controlling recoil would have more success with a PK and a skewed view may form that PK is "better" than other weapons, when in fact it's just easier to use vs underpowered legends. The fatties will get buffed eventually. And even if PK stays somewhat more reliable weapon vs them, I would say that would be good - it actually adds even more depth to the game.