bed liners

Just got a new dually long box. I want to keep the paint looking good so I plane on getting a bed liner of some kind. I would prefer a drop in liner over a spray cause you cannot take the spray liner out if you want and also you can never get the painted factory finish back if you have a sprayed liner. What liner would you recommend. I need something very heavy duty cause rocks etc will be dropped on it. Best thing I can find is something like this http://www.gmgoodwrench.com/accessoriesjsp/accessorydetail.jsp?make=chevrolet&model=silverado&year=2006&detail=06_SIL_BLB&sid=3352737169567169



Any other suggestions or opinions? Thanks