based on Jeremy TTAG's tests, i've used the PA M4-72 on several builds. it is very effective, and does a really good job of deflecting the blast rearwards to mitigate recoil, sometime you get spectacular fireballs coming back towards your gas block. however one thing i found out, is if your handguard extends up to near where the brake is at, e.g. 14.5" barrel with 12.5" free-float handguard, then you get burnt powder fouling all over your handguard and front BUIS. kinda a PITA to clean up afterwards, all those nooks n crannies, Hoppes #9 & Q-tips, e.g. keymod, picatinny. seems like you you need about 6" between the brake and front of handguard to avoid this. consequently, thinking of switching over to VG6 and/or LANTAC. humbug though with pinned/welded 14.5" configs. it's either that, or shorter handguards.
the VG6, LANTAC (and most others) direct the blast straight sidewards, instead of rearwards, which of course makes them less effective regarding recoil mitigation than the M4-72, so it's a trade-off.