well,
some breaks are designed to take out muzzle jump, some for dust signature, some for noise reduction (linear compensators).
im not sure of the verbage but there is a diff between a break and compensator and a flash hider. someone might be able to help out more on this without me doing a google search on it but...
i know that a bushmaster "izzy" break is one mean mother, i shot mine one time with out ear protection (dumb i know) and my ears rang for 2 weeks, i tried everything i could with that thing, that rifle went down the road (it was pinned on and during the ban)
the flash hiders that are standard on the milliatry M16 and M4 (bird cage type), help control muzzle jump to an extent, but mainly are for reduching the dust signature when shooting prone and suppersing the muzzle flash in low light, this is a dead giveaway to a shooting position from the enemy point of view.
compensators, do just that, compensate for things that the rifle does, muzzle jump, recoil, muzzle blast etc. i have a Kies blast master liner comp comming on my custom build that Scott is doing for me, this comp will reduce the muzzle blast and noise that will come off the 16 inch barrel.
hope this helps you out some but without knowing what muzzle devise you have now its kind of hard to nail it down for you.