I've gone years without one in my system, just never really justifying the cost. Now that I finally jumped into buying one, I'll never have a system without one again. Sound is so much smoother, more precise hits, and never seems to fade. I definitely recommend if you don't have one.
Only problem is the instructions are real unclear for charging it. You have to charge it before hooking it up. Ask someone who has done it before if your unclear of what to do. It's easy.