I really like my underfolder.
The carbine is my plinker so I have gone unscoped with the Ruger irons and a TRS25 RD on a 45 degree mount. It works really well for mag dumps on rolling targets at 20-30 yards. It's a chin weld as opposed to a cheek weld with the red dot but I keep both eyes open and it's fast.
The cheekweld with the irons works fine.
With the stock collapsed it is very short and handy and yet you can still have a 25 round mag in it and open and close the stock.
I prefer the carbine with a 10 round Ruger mag in it as it is slimmer and easier to carry.
I still haven't decided on the final sling. I installed a stud in the back of the stock.
The stock is very solid and ridgid both open and closed. It's a keeper.