One of the new "pocket 9's" will:
-Have notably less recoil (due to locked breech operation vs. blowback) despite shooting a more powerful cartridge and most likely weighing less. Also, the grip frame on a P-64 does about as much to distribute recoil as a hammer.
-Offer far greater ammo choices and (normally) availability.
-Have a better trigger. That's somewhat subjective but even the worst of those I tried was at least half the DA pull on a P-64. You can use a lighter hammer spring with good results, but I would need to send at least 300+ down the tube to trust no light strikes.
-Weigh less (did I mention that already?).
-Not cost a ton more (& that largely mitigated by cheaper ammo)
I think the P-64's are neat looking and mine (like most I hear about) was surprisingly accurate. Too bad the ergo's + blowback operation made it one of the least pleasant pistols I've shot to date. And I'm not recoil shy; that thing was just not enjoyable at all.
If you opt to carry one, practice - a lot. Same goes for any weapon there though. If you can afford another $75-150 bucks or so, the 64 isn't even in the same league as more modern pocket carry choices.
Funnel