I've got an Armalite that I built using the Noveske 12.5" Leonidas barrel. Noveske ships it with a gas block and gas tube. A bunch of the guys around here have shot it also. It shoots well, is accurate and I've never had any reliability issues with it that I didn't cause myself (a loose safety selector screw once). I've shot it suppressed also and she runs quite well. John Noveske knew his poop when it came to designing barrel/gas system combos.
As far as for POF. I've got one of their 12.5" SBR's that I bought (factory built, I didn't build it). To tell the truth, I don't see any real difference in performance from it compared to any of my other DI gas SBR's. And I really wasn't that impressed with it, and rarely even take her out of the gun box to shoot it. My shorty Armalite is my "go to" for my SBR's that are 7.62/308.
Here's the POF.
I've also got a 3rd shorty 308. Made by DSA. It's a FAL OSW. Now she's fun to shoot. The FAL adjustable gas system is probably the most adjustable of any out there. She's probably the heaviest out of the 3, but she's still pretty badass.