Airbag/Leaf Spring Lift Question

I'm going to doing some significant mods to my 2012DCLB, which includes a 3-3.5" lift. I've got an experienced shop doing the work, but have a question on the rear lift.

The shop is suggesting that I stay with the rear factory springs and just add the air bags. They say the unloaded ride quality will be better than upgrading the springs to something like Deaver Expedition springs. So the air bags will provide the lift/leveling and will also provide a large part of the suspension whether loaded or not...correct?

Based on my thoughts and some of what I read, this setup will not necessarily provide a better quality ride, especially unloaded? I'm thinking that adding a 2" lift spring in the rear will make the suspension less reliant on the air bags and more on the spring/shock system? Air bags would provide just leveling when unloaded.

As a follow-up, if using air bags, does it make more sense to go with a stage 1 leaf spring, versus a stage 3? The air bags will compensate for load, but will a lower stage spring afford a better unloaded ride?

FYI...going with either King or Fox shocks, undecided yet and eventually this will approach a full overland type build.

Thanks!