I don't think "deaden" is the right word. Obviously it depends on the quality of the frame, but I think aluminum is more responsive because it is usually stiffer and lighter. If you are just riding around town then steel might be more comfortable and durable when you lock it up to racks. If you're looking for speed, responsiveness, or lighter weight (though not much, I don't think the RR is a very light frame), then go with aluminum.