Don't know...
Got an SU16 and tricked it out and it get's 2" @ 100 meters with any given box ammo I've tried to date. Got a friends XCR that I bumm off him all the time and at the range and the same ammo I get the same bullet group results. Although he wins in a land slide when it comes to ergo's like bolt release AR style mag release and full quad rail and the real kicker,
A NICE HEAVY BARREL. But guess what...
With another $350 I got an AR pistol grip and MOE stock, a Vltor moded free floating quad rail, added an AR15 mag release but and oh ya my finnal "
Ah Ha" moment. I made a bolt release for it.

No I won't show you picture's. Yes it does work but no the stock no longer folds in half but who cares cause I got the pistol grip stock and it never did in the first place.
Oh ya all tricked out it still only wiegh's 7.68 lbs. I yes my trigger job took an hour to due but now it has a nice 4lbs trigger pull that is
SWEET!
Is it plastic?
Yep
Is it worth $400 to $600 depending on what it comes with?
Yep
Is Vault got a monoploy on the KelTec line so #####ing about the price going to do sweet bugger all about it?
Yep but Wolverine has the same thing with the XCR's too.
Do they both use screw's?
Yep
Are the XCR's more common?
Hell ya but the SU16 rifle just got released in Canada this year. So just give it a bit.
Do we all wish our government wasn't so F'd up that there was no such thing as non-restricted/restricted/prohib rifle's?
F YA! Cause if this was the case then everyone would just get an AR platform rifle cause thatz what we all wish it was at the end of the day. Sad but true.