I have some low-cost ProEars. Apparently they are missing some of the features (like using them with an MP3 player) and don't have as high a NRR as their Gold models, but they do amplify sounds nicely and they do clamp quickly.
I've found that even a NRR of 22dB is fine when doubled with foam ear plugs. The foam ear plugs have a NRR of 30dB, and combined with the muffs two things are true (for me) -
1. I can still hear others talking at the range, if the volume is turned up all the way. As we all act as RO's, "Range is cold!" is something you need to hear.
2. The combined damping is sufficient to sit right next to a guy with a .300 Win Mag and it doesn't bother me. Well, maybe the concussion wave is a little disturbing, but at least my ears are fine.
The other feature I like about the ProEars is that the batteries are easy to change without tools, as the battery holders are inside the earcups, under foam. This is much easier than prying the outside of the ear cups apart, IMO.
.30-06 Springfield: 100 yrs + and still going strong