I think the differences between these various "music" ear plugs is negligible until you get a custom set. We have 3 or 4 types and they seem similar in efficacy.
My suggestion, Marco, is that you try playing 2-3 hours in that band rehearsal room wearing 29db shooting ear muffs and see if you get a head ache. If you don't, then I suggest home made sound absorbing panels and custom ear plugs, or just add 21db ear muff to the earasers.
I made rock wool core panels for my son's practice room, and the difference is amazing in how much less painful the sound is. ( http://drummerworld.com/forums/showthread.php?t=100058