After a single round from a braked .308 Win two firing points to my right started my left ear ringing with permanent tinnitus in 2009, I don't go to the range without my electronic muffs. Never again will I "slip" one ear loose to hear what someone is saying.
I have used the Peltor Tactical 6S muffs for several years, and my only complaint is they wear out and quit working after a year or two (don't mean the batteries... those'll go dead in a day if you leave 'em on in your car.. which I keep doing...).
The "recovery time" after a shot is MUCH faster than the 'el cheapo Midway brand electronic muffs I started with.. those were damn annoying!
I just got a pair of Peltor 3M TacticalPro muffs for christmas, and like them better. They're not as small a form-factor, so haven't proved out how they're going to work in all shooting situations yet, but they're comfortable, the electronics are good (great amplification for range commands from mumble-mouthed range officers, and fast recovery after the "cut off").
I very often have a plug in my right ear even when using the electronic muffs... I want to keep the ABSOLUTE MAXIMUM hearing in my "good" ear now that my left has that constant "eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee" in it.
Peltor ALSO makes some other models that have built in radio's, or wired communication "ports" so that a shooter and spotter can communicate that way, while providing the maximum protection for your ears. I don't know much about those models, as I don't have need for them at the moment.
I HIGHLY HIGHLY recommend electronic "muffs" because they minimize the amount of time shooters have to spend yelling at each other to hear, and the amount of time behind the line when people just won't wear hearing protection just for that reason; they can't hear conversation.
Paul F.