Ok. So finally got to go to the range and try it again. Verdict: the gun shoots fine. Yeah, I'm still not jazzed by the loose play in the slide. I could call it "appropriately loose for a combat gun" (yet my G19 isn't loose and most would call it fairly combat competent); but I'll just call it ... loose. It's VERY MINOR. More of a mental image dissonance thing. I'd heard so much about the PM9 being machined to such tight tolerances, yada, yada, yada. I think 90% of that impression is the super strong spring.
Bottom line, it shoots very accurately when I take my time. Braced, I got a group where 10 of 14 rounds were within 1.5" of each other, and the flyers were no more than another inch and a half out. Performed every bit as well as the G19 in slow fire. BUT I suck at rapid double tap. And the culprit? Me and the trigger. It's just such a Loooooong pull that I'm dipping the muzzle by the time the trigger breaks and a round gets out. I'm consistently low (like 10" low) at 21'. Yet, to be fair, this is my first owned DAO gun and I've got less than 200 rounds through it, so it would certainly be a rush to judgement to write it off. Don't expect to see it on the want ads for sale tomorrow.
But for those who wonder PM9 v. CM9, I'd wager to say, the CM9 is just fine. I got to hankering really bad for the black and the fancy rifling in the barrel (which is FAR less important than the user IMHO). This isn't a target gun, and the difference between barrels, the slide stop and engraving are minimal at best. Your mileage may vary, but that's my take.
For now, it's a keeper. From here, it's practice, practice, practice. Thanks for the feedback and insight along the way. It did give me a lot to look at and try out when I gave it another shot, so to speak.