Thanks iamdub, The Arnott kits come with rear springs supposedly because the Z55/G69 springs are softer and will sag. I didn't see matching springs for the Bilstein's, thought I would check with you all for ideas.
They are a little softer, but changing the shocks wouldn't cause sag. If your ALC system isn't currently operational, then the air bellows aren't doing anything and the coil springs are already supporting all the weight. So, with new shocks or even no shocks, the rear will sit just as it does now. Shocks don't support weight, they just dampen movement. The air bellows on the ALC shocks DO support weight to supplement the coils, but that's not the shock portion. They're just air springs located on the shocks for convenient packaging.
If your ALC system is currently operational, then the rear is being lifted about 1/2" by the air system. Therefore, it will sit about 1/2" lower with those shocks removed, unless you install firmer springs.
Some people probably feel it's too soft without the air support.