@ScottyBoy
Ok.... I've been doing quite a bit of reading on this topic recently.....
My Burb does have the ZW7 rpo code for "premium soft ride self leveling" rear shocks. Nivomats. Like you said they are a big ass gas charged self leveling shock. No electronics, sensors, compressors, or links. Completey self contained.
Four setups one could have.... Standard springs/shocks, Z71 springs/shocks, Nivomat shocks/"softer rate" springs, and Auto-ride rear suspension (containing gas shocks with air bags on each rear shock, compressor, links, sensors, etc). Our old Yukon had Autoride.... Drop kit put the rear brake cable in a lower position, rubbed hole in air bag on shock, PSSHHHHHHHHHH.... leak! Pulled Autoride compressor fuse, rode on.
From what I'd read the ZW7 Nivomat equipped SUVs rear springs are softer. If you replaced the Nivomat shocks with "regular" it'd handle funny, sway, etc. Good to hear yours doesn't appear to be affected.
I'm currently just gonna run my Nivomats and get lower shock extensions. Mine rode/rides great as is and I see no reason to swap them right now. If I do... I'd prefer to go with Bilsteins. You can upgrade to Moog replacement coils or Bilstein coils.... Or Z71 coils which will gain you some height. 1/2"-1" height I've read.
Another interesting note: While I had my coils out swapping in the 1.5" coil spacers... I compared the ZW7 Burb rear springs to my stock 05' Yukon Autoride coils. Autoride coils about 1" taller. Coil diameters "seem the same".... Rates?!? Idk..!?!
Burb left, Yukon right: :hmm: