I started with airbags then added Hellwig load pro springs. My experience is that if you need a lot of pressure in the bags to level the truck you'll get more sway. There's friction between the leafs of leaf springs which work to limit the rebound from compression. Airbags have nothing to limit their rebound. IMHO, air bags are good to compensate for a little sag and the ability to adjust pressure make them a good choice for minor leveling. On the other hand, if you have a lot of sag you're better off with steel since the higher pressure in the bags will cause more rebound and give you that bobble feeling driving down the road.
I admit the ride is a little stiffer with the springs, mostly due to the way I have them preloaded. I believe supersprings can be adjusted so unloaded they have little influence on the ride. But I never expected luxury car ride on my truck anyway...
My $0.02