I picked up a CMR-30 last fall, first 100 rounds ran fine then it stopped, bolt came loose from the carrier. Shipped it back to KT on their dime and it's been fine since (so far).
Very accurate, really nice trigger out of the box for this price. Small enough and light enough it can be shot like a pistol with the stock collapsed. Really not much bigger than my Sub2K when folded. And I wish my Sub2k had a trigger half as nice as this one.
I've also had a PMR-30 for a few years. It's been interesting trying to find ammo it likes and breaking it in, ran OK at first, then it didn't til I learned how often I needed to clean it and how to load the mags. But still occasionally chokes on it's favorite ammo, seems the slide is overrunning the next round, I give the slide a little pull back and the round pops up and it feeds fine. May try to add some weight tot he slide to slow it down a bit.
But the CMR-30, it runs ALL ammo, doesn't care if it's 30 or 40 grain, and groups the cheap stuff as well as the good stuff. Which is nice compared to my PMR-30 which can double it's groupings depending on what ammo it runs. And both the old pistol mags and the new carbine mags seem to run fine in my CMR, so I know it's not mag related. I'm guessing it's the simplicity of the blowback carbine vs the hybrid system in the pistol.
I don't plan to get rid of either but the carbine is quickly becoming my favorite of the two. Time will tell how reliable it is.