I think there is more time spent polishing the trigger bar on the steel framed pistols, but I can't verify. My P9 has a trigger just as nice as my steel Kahrs, but I don't know if that's just because I have 20 years worth of rounds through it or if the Premium series pistols also get more polishing time.

My CM9 had a gritty, creaky trigger when I got it. I took off the blowout panel and polished the trigger bar and inside the radius of the spring where it contacted the bar. I took pieces of sandpaper from 800-2500 grit, folded them over, and rubbed the spring on it. My Dremel and a bit of Flitz on a cloth ball shined the trigger bar to a mirror. Then I dabbed a bit of grease on the bar and things were much better.