I've run three different 11.5" barrels with a Surefire can...BCM CHF, BCM ELW & Sionics RGP.

Sionics RGP is the smoothest running of the three and the least overgassed. BCM ELW and CHF-govt are both about the same. I agree with Wake27 about the profile and I no longer own the gov't profile barrel. Both the Sionics and ELW have somewhere is the 3k run through them and both have been good performers with little issue. (One blown primer using the Sionics). Sionics is heavier than ELW, but runs smoother suppressed. I've run them with an A5H2 or H3, carbine with H3/Sprinco blue spring and with Geissele super 42/H2. The best performance has been from the A5, the carbines have not been an issue, just run a little harder. If I were buying another 11.5, it would be the Sionics 11.5 RGP for its balance, accuracy and smaller gas port/smoother operation. My $.02 using both barrels on ranges, classes and hunting.