Just got back from function testing and zeroing the optic on the Dissent (I did a preliminary boresight at home beforehand). Ran 250 through it - a mix of 147gr and 115gr range food-tier ammunition.
After ten rounds to zero at 25 yards, ran some more to get an idea of what the hold is like at 50 yards and the rest just to see how well it functions.
Short form - it was dead nuts reliable, locked back on empty every time and a ton of fun to shoot. Minimal recoil or movement (certainly miles better than any blowback AR-9 I've ever shot), the trigger is super crispy and fast and it's also quite the conversation starter at a public range, though that may just partially be due to all the stuff attached to my example.
Minor quibble - the CMMG magazines didn't seem to want to drop free without a little help so I found myself stripping them out manually. Maybe they'll wear in to the point where they drop on their own, maybe not. Also, loading them all the way to 30+ rounds is way easier than doing the same with Glock mags since they're double stack/double feed.
The only change to the AR manual of arms is the front charging handle and that's really nice in practice, since you can lock the bolt back just using your left hand and while it's not as cool as the HK slap, I did enjoy dropping the bolt from there while reassuming my grip on the handguard instead of using the standard AR bolt catch on occasion.
Will need more ammo (particularly hollow points) through it to give an unqualified recommendation, but I can definitely say that it's a great shooter and a pretty solid giggle generator right out of the box. There's arguments both ways for a "bag/truck gun", but the Dissent is definitely a really nice one of those so far.
EDIT: Based on the ejection pattern, this thing will definitely be a bad time if you're left-handed, so there's that too.