I've had the no-lock 340PD for EDC over 10 years but don't carry w/anything but +P. Magnum rounds make fast, accurate follow up shots very difficult, at least for me.
The "best" gun is the one you always have on your person...... never the one that's higher capacity or more powerful BUT is left at home in your safe because it's too heavy and bulky to carry.
+1. That super blaster that's too big/heavy to carry Comfortably will, sooner or later, be left behind. 340's (PD or M&P) are great to carry. They are a good bit less than optimal for shooting with hot loads. That said, they are doubtless the baddest lightweight carry pieces out there. Whatever you carry, be sure YOU can shoot it with the loads you carry. If you can't do that, find a lighter load. Having Magnum power is great, but ONLY if can hit with it. A hit from a model 43 will beat a miss with a 340