I recently bought the SB Tactical SBPDW "brace" for my pistol. It is a 10.5" barreled LWRC piston upper in 6.8 SPC. It shoots like a bloody dream. I used BUIS for a while figuring I would put a red dot on it when I could but I went a different and unexpected route. I recently upgraded the scope on my AI AT to a NF 7-35x and therefore all my rifles got an upgraded optic as everything was moved. When I got to the end of the upgrade chain, I had an ACOG TA31RCO-M4CP left over.
I ended up throwing it on the pistol and I have to say it is pretty damn nice. The "brace" turns this pistol into a manageable machine capable of accurate fire.
I am not suggesting that you go and buy an ACOG but a scope will definitely be worth it if you use a brace like I bought and this is something I would have laughed at prior.