Slick Rick: We have the same truck (earlier model year) and have been carrying an 855S for almost two years. The truck handles the load amazingly well - and we're running stock.
Since this is our second truck and camper set-up, we have something to compare it to. Previously, we had a non-slide Lance 820 sitting on a F350, super cab, V10, 4x4. This combination also handled very well, but these new 350's are really much more stout, when properly equipped. In fact, our new truck carries the heavier 855S even better than I thought it would. We are very happy with the set-up.
Slides are a personal preference, but given the choice, I highly recommend the 855S. The extra space is well worth the weight, cost and maintenance that may arise. Take your time and think it through, so you buy the right camper the first time around. It's cheaper that way.
Good luck with your decision.