I just bought a Sub 2000 and put 500 rounds though it on the weekend.
Thoughts:
-It's not cheaply made. I'd made to keep it inexpensive. Barrels are 4140. Other materials are polymer reinforced Zytel.
-I had 10 stoppages, all of them stove-pipe type malfunctions. I was using 115g MFS Ammo and I've read that the Kel Tec likes heavier ammo, especially during the break in period. This particular rifle has about 1000 rounds through it so it's well into it's break in period. These type of malfunctions are unacceptable, but I'll try it with heavier ammo before I decide what to do with it. I'll try polishing the bolt and checking the receiver tube for burrs. Also, being a blow-back action, it s**ts where it eats, and MFS ammo really gums it up.
-It's very light, weighing just over four pounds. You could easily carry it in a backpack all day and never notice it. The push button safety can be operated with your thumb and the trigger is Ok. You can get a good C-clamp grip on the forearm to control the snappy recoil. About that: You really notice the recoil! I have a nice bruise on my shoulder after yesterday's session.
-The sights are very crude. Despite the great design work done on this rifle, they s**t the bed with the sights. You really have to get into the stock to use them. The rear peep is fine but the front sight should have been redesigned long ago. The nut and screw actually backed out during my test. Luckily I found them in the dirt, and was able to screw it back down. If you have a Sub 2000 Locktite this area. I finally figured out how to adjust the sights and once I did it was right on at 15 yards (if you play the offset) and perfect at 75 yards. It hit the 75 yard gongs with authority.
-It requires some training to get used to the manual of arms. I think I've got it down and may post a video about that in a later thread.
-Glock mags are a nice feature and mag changes were reasonably fast. Gen 3,4 and 33/10 mags dropped free.
EDIT: One other thing: Field stripping for cleaning is extremely easy to do. Pop a pin, pull out the bolt group, clean away.
I'll be doing a full review sometime later, but that's all I can think of for now. If it worked 100% I'd probably feel a lot better about this rifle, but for now the Jury is still out.