Hi mate,
I have a pair of exactly what you are talking about, had a resin injected into my ears at a hearing specialist, then they sent them away and about three weeks later i received them back as CENS pro flex hunter.
They weren't cheap, but IMO worth every penny.
Its nice to shoot rifle / shotgun without realising you are wearing bulky ear muffs, feels more natural and they are more effective as they are a perfect complete seal of your ear.
The batteries last about 20 hours - they are hearing aid batteries so not expensive.
When wearing them, you get what some of the sportac guys will have experienced - a kind of super hearing, the ability to hear other people talking a long way off, or your quarry moving in the woods!
Hope that helps you make your decision - i wouldn't wear anything else now