Well, basically the fox shocks (as do most) have oil inside the body which acts as a dampener for when the piston moves up and down. When you "revalve" your shocks you can either increase or decrease the rate for which the shock oil flows back and forth as your shock move, hence changing the characteristics of the shock. If you increase the flow rate your shocks will be softer, if you decrease it they will be harder. That's the beauty of the high end shocks (Fox, King, Icon, ect) you can tune them to you preference, or rebuild them if needed. If most of your driving is on road, I think a full OME setup will be more than enough for ya, but if you really want the Fox's I say go for it.