I've got a worn out disc in my lower back and I got a back shell ment for motorcykle riding with a integrated kidneybelt and it works superb, has saved me a couple of times as well....
Ditto as well.
I find I sit more straight and don't slouch or ride lazy when I wear one, plust at the end of a long day, when I take it off its refreshing!
I had lower back surgery May '07 and NEVER ride without my back brace. Mag's back hurts some too and he has a Fox kidney belt but I wear the one I got from my physical therapist... "LumboLoc".