Where suppressor technology is at the moment, I would seriously recommend going with a low back pressure suppressor design.
However it would be advisable to be able to try out the choices before buying to verify the manufacturers claim and to see that there is no negative effect of the design ( too loud, large muzzle flash etc. )
It is possible to have a suppressor design that has good sound suppression, excellent flash signature reduction and also keeping the effect on the bolt carrier speed under 10% increase ( with more traditional suppressor models it is c. 30-40% usually on 5.56 rifles )
Best Regards!
Tuukka Jokinen
Ase Utra sound suppressors