Let me know what they say, but I'll tell you my take on this (and of course that take could change as you find out more about this company and this barrel).
If this barrel was for something like a primary bug-out rifle or something like that, then I'd want to stress reliability and flexibility over anything else. The 11.5" with a carbine-length gas system is a proven design, and in theory it should run with a wider range if ammo pressures than a mid-length.
On the other hand, the mid-length 11.5" should be a little softer shooting, especially with a silencer. And that can mean faster follow-up shots and longer parts life.
But I guess it all comes down to real-world testing; maybe a mid-length gas system is a better choice for all-around suppressed and unsuppressed use on an 11.5" barrel, and this company is just the first to figure that out. I'll say that I was little skeptical of running a non-standard gas length when I got that 14.5" mid-length barrel, but there are two things that convinced me that it would be fine: First, it's a Daniel Defense barrel and they definitely know what they're doing. And second, my buffer system is a VLTOR A5 system, which mimics an M16 buffer system in a collapsible stock setup, and is more flexible with different gas pressures.
It's a little more difficult for you since this setup isn't as common as a 14.5" mid-length and this company isn't anywhere near as proven as Daniel Defense. But I say go for it and give this barrel a try if this is just a recreational build and you can afford to take chances with reliability. You might end up with a better setup in the end.
