http://www.4x4wire.com/jeep/tech/susp/xj_ome_tflx/

I put this same lift in my 98 Cherokee and love it. Install took us about 4 hours for both front and rear springs, shocks and bushing all the way around. Simple tools, 2 guys in the driveway.
Pothole littered roads are smooth at 40 MPH, washboard is'nt scary and I have yet to hit the bumpstops.
Can't think of any downside, ride is very smooth on pavement, not stiff at all. 1,000 miles later I'm still at 3" on all 4 corners.