Installing them on a CF barrel is no problem. I do not recommend removing them. If you take them on and off very much they will lose their timing in reguard to port position. I can provide a thread cap but again am not real big on brake removal.
Have you ever heard of Montana muzzle brakes? They claim an extra ammount of velocity and they produce in one incident for sure.Several friends of mine have these brakes and we tested one against my rifle which is a .338/300 RUM with 30" barrel the friends was a 28" barrel with identical brass and load it bested mine by over 100fps there is something to it.(friends rifle identical cartridge)
Were the barrel lengths the same I would agree totally.And knowing that both rifles shot within a few feet per second before the addition of the Montana brake I think the folks making the brake are on to something.The method you state would be the best test...