you must be referring to the MC1sc. It takes Glock 43 mags and I think Sig Sauer sights.
Also has a pretty unique takedown design where the striker assembly comes out first-- I guess that makes it a lot harder to have a ND when trying to take the gun down before cleaning.
Apparently Mossberg's first ever gun was a pistol so this is somewhat of a return to beginnings. There are some reviews out there, i've watched one from TFB TV and one from Hank Strange. Both quite favorable, reportedly pretty similar to the G43. It's supposed to be reasonably priced, around 4-450 when they come out, then they'll hopefully drop much lower from there.
I'm in a hopeful "wait-and-see" mode... If prices drop significantly in the future, to like $300, I may be interested in snagging one. But currently you can get a used G43 for the same as what Mossberg is planning on retailing the SC1 for..
Handled one at a.b. in Lafayette yesterday. $380. I have to be honest. It felt great in hand. Pointed so naturally for me. I didnt get to shoot it, but I would've liked to. If I see a good used one, prices come down/gun fund goes up, I'll be picking one up. To me it felt better than the glock, s&w, s/a offerings.