I exchanged email with some guys who have the Rubicon Express spring-over conversion kit installed in their Jeeps.

Regarding the performance:

• Jason Haller wrote:
  The spring-over is awesome. I scored a 937 on the RTI ramp here at our local club, but the ramp is steeper than norm. It's 23 degrees instead of 20 like that used in the magazines. In other words, I was 6" short of a full pull. :) I think the biggest reason that I didn't go all the way is the thin tires that I run. they are only 33x 9.5's That doesn't leave enough weight on the spring to make it droop as far as possible, but they are great of road, and besides, you hardly ever have to climb a ramp. :)
  Well the spring over is definately cheaper. I spent about 7 on my 4" explorer kit. I was happy with it, but it just wasn't soft enuf. I would not recommend a 3 or 4" lift anyway. Remember the taller you go the stiffer the springs are going to be. You probably get more flex with your 2" than any with a 4". I still do rub my fenders in the rear, actually the nerf bars too.
• The spring over is the only way to attain a lift this high on these things and still maintain ride quality. Also if you really think about it a re-arched spring will have lots of compression travel but not much droop because the spring is already drooped at the start. If you stick with the stock leafs which are flat you will have exactly as much compression as you do droop. A shackle lift will not net you this much lift and longer shackles put undue stress on the shackle mounts and are also more likely to break themselves due to their added length.

• I have not noticed any quirks that i would go as far as calling squirly. I am thoroughly pleased with all aspects of the conversion.
• How does it handle around town? Handles as good as it did before the spring over with the exception of 2 things. I left the rear track bar out for better articulation and that causes a little rear sway. It can be reinstalled if extreme axle articulation isn't what you are wanting. The other thing is that my shocks were worn out completely before the job so my ride actually is stiffer than I was used to but if the jeep had good shocks to begin with it is probably the same.

Driveshaft vibration is a concern and may require a CV driveshaft. However, the instructions are quite precise regarding the angle of the spring pads so for many rigs, there will be no vibration even if you have a non-CV shaft. It largely depends on the original length of the stock driveshaft. In my case, I've already got the MIT tailshaft eliminator on my xfer case so I'm going to give it a go without the CV shaft first.

One thing you may be wondering is why I'm buying a kit instead of fabricating my own since the parts are pretty much available anywhere (and because I seem to be such a cheap SOB). Well, the main reason is because my Jeep is my commuter vehicle so I can't leave it up on blocks for a week because I've forgotten to buy this or that or something doesn't fit. I need the assurance that I can start working on my Jeep Friday evening and then drive to work Monday morning. The other reason is that I've heard of people having bad experiences with spring-overs. At least with this kit, I know the components and installation will be identical to those of the people I've spoken with who've had good experiences with their spring-over conversions.

Well, check back here in February or March to see what I think once I've finally bought and installed the kit. It should be interesting.