My complete setup is as follows:
RC 4.5" Lift (Full Spring Pack)
Control Arm Drop Brackets
Nitro Shock Upgrade
Steering Stabilizer
I had done a lot of research on

before buying all of the above and heard so many mixed reviews on RC, I wasn't really sure what I was getting into. However, my XJ is a 1990 and I wasn't about to put on a lift kit that cost more than what I paid for the car, so RC was in my price range. I'll start by saying, I am not a mechanic person by nature and really this was my first major automotive project.
Pros:
Jason at RC (GRIMUSXJ99.) Gave me a good price, and got it shipped it out right away. I appreciate his responses to both the good and bad reviews on here I read here and was a major factor in my decision to buy RC. Kit arrived only a few days from ship date (I'm pretty sure my UPS man hates me now though, spring packs are not light!)
Kit is solid, and runs quite well. To compare what the suspension "feels like" (in the best way I can put it) was like going from an SUV to a Wrangler. Very bouncy. Definitely achieved exactly the look and feel I was going for with BFG 32x11.5 KM2s. I'm sure the control arm drop kit helped out with the ride.
Cons:
Biggest complaint by far is the quality of instructions. I would seriously suggest hiring a technical writer and having him install the kit with one of your mechanics/engineers and rewriting the instructions from scratch. A good start would be a "required and/or suggested tools" list, a list of what is in each bag and/or box (only one bag's contents is listed, the rest is up to you to find!) Many of the specified bolt sizes were incorrect, steps were out of order and/or repeated incorrectly. Some of this may be due to the varying years of XJ's; not sure. Also, minor nitpick but there are also lots of spelling errors - really just adds to the unprofessional feel of the instructions. A little reference of bolt sizes and torque values would also help (if you're installing on an XJ older than 1995 you can bet you are going to at least break one or two of the original bolts and be heading to the auto store looking for a replacement.) Also, if there was some way to integrate the CA drop kit instructions into the lift installation instructions (since after all you suggest it should be purchased with the 4.5" lift on your website) that would be great, I kinda had to figure out where to fit those in during the lift kit install. Minor gripe though.
Also, as many have commented on.. the trackbar relocation design is bad. You should not run this design very long without getting an adjustable track bar. I say this because I ran mine for about 500 miles (post lift) and last night I put on a JKS adjustable trackbar. When I took off the relocated stock track bar, I discovered that the "relocation" hole had stretched to almost double it's original size, and the amount of steel I had holding the track bar in was only 2mm thick. The bolt had bent into a "V" shape. Not good. I would guess that in the next 500 miles that sucker would have popped off, and god knows where. If you would like me to point out errors I found in the instructions I would be happy to do that to help.
Overall:
I am very happy with the kit and would buy from RC again. For the price, you can't beat it. Jason is always on the forum and remains objectional yet helpful with any problems you might have. My Jeep rides better now than it did pre-lift. The instructions were terrible, but there were probably some points where experienced mechanics or people who have done this before could have read through the lines. I expected better instructions for something you pay a pretty big chunk of change on though. Trackbar relocation needs to be redesigned or you need to start including a adjustable track bar in your kits (even if you have to charge extra $$$.)
Oh, one more positive is the RC website, which is graphically well done and easy to navigate. Might want to have same company help with your instructions? Just a suggestion.