XREAS is very good for cornering on-road (it's main purpose)...helps to reduce body roll. As you take a corner, the 4runner will rock towards the outside. XREAS senses this and hydraulically pumps more fluid to the outside shocks (by drawing from the inside shocks) in an X-pattern. This helps firm up the outside shocks, and softening the inside shocks. Thus, you have less body roll because the outside shocks are pushing against the body lean.

It is cross-linked: left front shock to right rear shock; right front shock to left rear shock. Thus, X-shaped.

XREAS shocks are MONO-tube shocks and thus, are high-pressured shocks. They should (in theory) last the life of your 4runner or for a very long time. They are more efficient in damping the ride, but they are significantly firmer than regular low-pressure twin-tube shocks (found on non-XREAS 4runners).

In off-roading?? XREAS probably won't do much in off-roading. However, because it has MONOtube shocks (high-pressure, quicker reacting), XREAS suspension is more efficient in controlling your 4Runner body motions over bad terrain. Since monotubes are more efficient, you have less chance of shock fading/overheating. HOWEVER, monotubes are more fragile than twin-tube shocks...therefore, if a rock hits it, then it will have a higher chance of damage.

Hope this helps.