only real drawback to triple stack bags is if your running a c&c rearend . you cant run the bags over axel directly. due to the rear end being offset. you could cut into the cast and have them raised or go behind. theres actually a topic on here about it.
Mine are mounted behind the axle, rides awesome and lots of lift. The only issue i have is my shocks are extended before my bags max out but dont really need that much lift anyways.
I have firestone 7795 (i think) and it tows great. I posted a pic in the show your dually pullin thread and i had 35 psi in it riddin on the highway about 1 inch off the ground