In considering which pads to use for downhill work it is essential to understand your own brake system. Some hydraulic systems use fluid lines made from nylon or plastic and can be prone to softening and swell if overheated.For this reason they are not too keen on using pads in their systems that generate too much heat such as sintered pads. 

If Downhill is your riding style, EBC MTB red grade brake pads will be a great choice. Their lifetime will be relatively short but they will assist with improved brake performance. Low rotor damage and minimal heat transfer into the bikes hydraulics is also a feature.