I almost went with the large drums on the Mor Ryde IS but I'm a long way from Elkhart and don't want to "have" to go back. I run exhaust brakes on all my trucks, which also all have disk brakes. I have warmed up some of my trailer drums and have had less pedal than desired more than once. Usually in traffic when you can't avoid using your brakes because other drivers feel the need to fill the hole you left in front of yourself. Like Ben at Mor Ryde said, "you are one panic stop away from wishing you had the disks." I'm usually running around the western states during fire season, and they all seem to have their share of hills. I rarely ever use brakes on the hills, and like to know they are there when I need to stop. We should be picking up our 3585RL the second week in January. By Spring we will have several thousand miles on it and I'll post my thoughts on IS with disks.