I would agree with your conclusions here. I think Apex makes the most drastic difference, really, because of the mitigation of the gritty take up.
I have never used just the PRP drop-in kit, but the complete competition kit. Which did produce a VERY good trigger... however I wouldn't feel safe with it for carry. It had about as much movement as the trigger in my Springfield TRP 1911 and wasn't much heavier. VERY good... but a little scary for duty/carry (it's a competition trigger after all)..
The Apex DCAEK provides a great trigger for a striker fired gun. The newer triggers also have a better reset than the older ones. My newer M&P Pro 9 is evidence of that. In fact, after polishing the contact surface of the trigger bar where it interacts with the striker block, there is basically no grit at all. The pro trigger breaks to the rear like the Apex kit does, so I don't even need the Apex kit in my Pro series - but I definitely consider it a requirement in the standard models.
Glock 19 G4 Gray | Glock 17 G4 FDE | S&W M&P 22 | S&W M&P 45 | S&W M&P 9 | Sig P226 MK25 | Sig P229 Extreme | Sig P227 Carry | Sig P320 F | Sig P320 C | HK45 | HK 45 CT | HK USP 9 | HK USP 45 | HK VP9
Daniel Defense DDM4 V4 | Arsenal SGL 21 | ASA SBR | Savage Mark II FV-SR
Mossberg 590A1 20" SP | Mossberg 500 Cruiser