Dan, I like charlie have the Speedtech rear, with coilovers all around, plus the usual upgrades to the front suspension. I can tell you that when I swapped cars with my buddy and I drove his 2012 ZO6 carbon edition Vette and he mine ... when we got out he looked at me and said ... "wow, that thing has a nicer ride than my vette" , and he was right, his vette was much harsher than my 69'.
I cannot comment over other suspension providers, I've heard great things about the Ridetech but I was looking for more adjustability and have to say I am VERY pleased with the Speedtech. I just upgraded the front to the Speedtech Chicane and am looking forward to seeing the difference there as well ...
69' SS/RS X11 PRO-TOURING E-FORCE LS7, DSE Sub, T56 MAG, Recaro, Wilwood disc, Racepak IQ3S, SpeedTech TA/JRI CO's, Pro-Venom 250s, Forgeline CV3C 20/19 - SOLD