I'll second Pork Belly on leaving back membrane on.
Up until recently I did remove it before smoking. Having read awhile back leaving it on helps hold moisture in the ribs that's the way I've rolled the last two times. Can't say definitively that's the case but I believe it's helping. It's just my sense of it... if that makes sense...lol
The only way to actually know would be to cut a rack in half and smoke half a rack peeled and half not peeled with the same placement in the smoker. Even then without a moister meter(?) the moistness of the meat might not be apparent.
Now there's a smokin-it test for someone