Our agency SERT was issued new 6920's with a 10.5 bbl and Gemtech thread on (permanent rockset) cans. Most of the rifles have been so ridden with malfunctions that the guys either pulled the can off, or just went back to their old rifle. Its no fault of the rifle, but they were not equipped to mechanically work well suppressed. I'm no gunsmith or armorer myself but i know we put an adjustable gas block on a problem rifle and it worked, rather than 7-10 malfunctions a magazine. Rather than just buy 30 adjustable gas blocks and or different buffers for each problem rifle, the agency continues to ask Colt why the rifles dont work, who of course says send them to us and we'll give you new ones. God bless them. So I guess as part of your process I would humbly suggest (depending on what rifle you are using), to include the budget for an adjustable gasblock and buffer for each rifle.
As far as the cans go, is there a reason to permanently mount it, rather than a quick detach muzzle device of some kind? The only thing ive been able to figure out is price. The Gemtechs we have were pretty inexpensive and seem of good quality. I am no expert or anything special, but i figured i'd share what we've recently experienced.