I mostly travel in the Western mountains and have had no problem with the Western grades. Occasionally I am slowed down but for the most part, so are the DP's. Not all DP's can roar up a mountain grade, and most owners do not want to anyway. I used to have a DP and changed because of floor plan and do not miss the slight power difference. As far as decent braking, again, it is more technique than anything else.
The facts are that during your travels, in the East or West, the steeper grads happen so infrequently that they are really nothing to be concerned about. For 99.9999999% of your travels, your engine, as with anyone else's, will do just fine. Actually I have never heard of anyone on this forum stating that their coach COULD NOT make it to the top of any highway hill. It might take a little longer but they all got to their destination. So will you.
