Well I can tell you about the ride on the BDS 2" kit, it's great. I have this kit on my YJ with a set of TrailMaster SSV's. I didn't have to use a t-case drop (but it did come with one), dropped pitman arm, or extended brake lines. I have had this kit for a couple of years and havn't seen any sag at all.
I agree with the 1" body lift maximum, and am planning on using one myself.
As for the cost of the BDS 3.5" kit, it was less than $600 but didn't include new shackles or brake lines.
95.5 YJ with "stuff"