I have the Rough Country leveling kit. 2.5" front, 1" rear. The main benefit is greater ground clearance.
This is a spacer kit that fits between the top of front strut and the body mount; and on top of the rear springs. With this installation, there is no change in the length of the strut, nor the actuation length of the shock. Thus the ride is the same. Space kits that go between the spring and the spring mount do "preload" the spring and change the shock actuation length, but that is not the Rough Country set up.
Because the changed angles of the UCA and LCA, an alignment is mandatory. I have not noticed any change in handling. The front drive axles are at more of an angle, thus the life of the CV joints may be shortened. For larger front lifts, people will do a front differential lowering kit, but seldom is it needed with only a 2.5" lift
The rear shock does actuate lower on it's range, but it is possible to get extended length shocks. Because the spring is the same, and operates over the same range, there is no change to the rear ride.
Because the 4Runner has a live rear axle, a lift kit does not raise the axle, thus the lowest point becomes the rear differential. If you are concerned about that, then you need a skid plate for the rear diff. The only way to raise the rear diff on a live axle vehicle is with bigger tires.
