I have used a bunch of different smokers (gas, electric, charcoal, sticks & now, pellets) and I think that the bark, or lack therof, depends on the amount & type of rub more than anything else.
CBJ # 22569
KCBS BoD Judges' Advocate
Member of the 100 Contest Club
Possibly the only judge ever to get an award from a bunch of cooks
UDS 075 UCB WSM and a bunch of other stuff.
The above post is only my opinion - mine & mine alone.