I bought the stage 1 version which included RK's RRD shock and bumps.
I bought some synergy brake brackets as well, which btw served as a great mount point for my rock lights as well.
I found the kit a good starting place as I want to use want I want to use on my jeep, I do not necessarily want RK arms or new brake lines etc....so for my purposes was fine. The components are well built but you may find some folks who are/were worried about the rear trackbar bracket. It does have a different design than the ubolt type ....does seem to create a weird fulcrum but...I decided to keep my RK bracket, time will tell..
I have about 2k miles on the lift and its performed well on and off road so far.