I had a 32' rexhall with the Ford V-10 before I got the current DP. The gasser actually accelerated much faster than the DP, and it could climb hills just as fast, if not faster than the DP. You can get underpowered DP's too and load them down and have trouble with hill climbing just like you can do with a gasser. The trick is just make sure you have enough power for the size of the rig and what you want to do with it. If you're planning on a towing 15,000 pounds of stuff in a car hauler trailer behind you, then you probably want a DP with a big engine. Otherwise a gasser will probably do everything you want.
One of the main reasons people pick a DP over a gasser is because the ride is so much nicer with the air ride suspension of a DP over most gas motorhomes. Drive both and see for yourself.