Well two of my friends have been running the same set up i am using out back for years now. After riding all around town and offroad in those trucks I determined that was what i wanted to do. I set my shackle angle the same as his because he has never inverted a shackle and doesnt seem to have any problems with axle wrap. with the 35s my tires rub well before the dual shackles even reach their extended limit. He runs 37s but the same thing applies to his rig.
I was against doing the double shackle for a while but i really like how my rear end flexes and thus far street handling has been fine. If I hit speed bumps at 45mph my rear end hops but i try not to do that too often so its not really a problem.
ive been driving it on the street for almost a month now and it handles great. without the little stablizer bar up front anymore the truck sways a bit more on corners, but i was prepared for that so its nothing more than correcting the way i drive. I can actualy flex the truck a lot without the shackle unloading. in fact, with only 2wd at the moment I cant even flex it enough for the chevy shackle to come off the frame. As time goes by and i start to wheel the truck i will let you know if i still like the setup. so far though, im stoked