I've used Peltor and Pro-Ears for years...One of the quality differences is the amount of time that the noise canceling circuit takes to restore the listening after the shut down from the shot..as well as sensitivity to background noises...
In a hunting scenario it may not be that important whether it's one or more seconds, but in competition, where range commands are given by a safety officer, that time lag can mean the difference in understanding what is being said when other gunshots are present..
The lower quality ones will amplify your breathing and pulse noises if turned up to hear minute sounds and are really bad in a breeze...Your better quality ones usually have much clearer sound quality without the background distraction..
It pays to try several in a store if you are buying your first pair...If you find one that suits your needs, then either buy it there or order mail order..Put on a pair and walk around the store to check for the pulse and heartbeat noise, as well as having someone create a loud noise to see what the sound recovery time lag happens to be..
Also, compare the type of batteries used... AA and AAA are readily available if needed, NP-123s are about $15 a pair... some models also have auto shut-off circuits that prevent battery drain after a period of time..
