After an overnight of contemplation, I'll change my comment: While I won't pay "be the first to have one" price, I will be on the lookout for an opportunity to own one of the carbines at a realistic price.
Overall length of the folded stock unit is about the same as the AR PDW I'm currently hauling. Surely, the 5.7x28 isn't excessively loud and should be a better choice for the 'there's a coyote-choot'em' scenario.
"That chambering does nothing for me. I would rather see one in .22mag or .30 carbine. Until then I will stick with 9mm."
That's reasonable BUT in some circles ANY rimfire is considered less trustworthy than a centerfire. The 5.7x28 is basically a better performing replacement for the 22WMR which feeds better in a stick mag. Once upon a time, I owned a semi-auto 22WMR--right up to the time when I experienced an OOB discharge due to a malfunction related to the rimfire design..
I don't understand why the 30 carbine hasn't seen a resurgence although OAL may be a factor. From an armchair perspective, the 30 carbine isn't a bad option but no one has really shown interest.
The initial 5.7x28 design was tailormade for PDW use including armor penetration capabilities although there's only so much that can be done with a .22 and 40 grains.
Granted, the 9x19 is fine until you need ranging capability beyond 75-100 yards or armor defeating capability.
The AR-57 uppers are becoming available again, and rumor is there will be a pistol/SBR version coming out in the next year. Takes FN P-90 magazines, mounts on an AR platform lower. Think I would consider that route unless I were invested in the 5.7 as a pistol round with the Ruger 57 as a companion.
Nothing particularly wrong with this offering, just seems like there are more compatible options based off an AR platform.
Saw one and handled it at a local gun show Saturday. Very nice. After researching the 5.7 x 28 round and realizing that the Secret Service is using it, I ordered one a few hours ago (at way, way less than MSRP).
Also have 200 rounds of ammo and two extra factory magazines coming.