Ummmm...this is just me, but...
...I'm not real big on carrying ANYTHING of significant value in my rear pants pockets, whether it's my wallet or a gun in a wallet holster. Just about every "crime prevention" guidebook and travel guide will tell you about how vulnerable your back pockets are to pickpockets, especially in large cities or during crowded, high-foot-traffic periods like Christmas shopping season in malls. If I lose my wallet with my ID, cash, credit cards, etc. to a pickpocket, that's one thing...it's entirely another thing to lose a GUN with a paper trail leading to ME as its last known purchaser.
I now carry a very small wallet(really just a leather business-card holder) with my DL, CCW, a couple of credit cards, and a little folding $$ in a buttoned or Velcro-ed shirt pocket, or in my front pants pocket so that I can keep my hand on it in crowds. I likewise carry my S&W 642 in the other front pants pocket, in a Kramer pocket holster, so that I can also keep my hand on it in crowds.
Back pockets are now for relatively inconsequential stuff like hankies, lighters, mints/gum, spare mags/SpeedStrips, and a SureFire A2 Aviator w/pocket clip(yeah, I'd hate to lose that $150 flashlight, or my $30 spare mags, but I'd hate to lose my wallet or gun even more, and my left-rear pocket is about the only space left that will hold it).