Well, as someone who just drove a 35' WH gasser and a 40' 400 HP Cummins over the same road from Reno NV to San Jose CA, the DP is quieter in all aspects. Climbing, and just plane running down the road. My main complaint with our gasser was the fan noise when climbing and the fact that it would kick in when necessary. Acceleration is pretty evenly matched, but the DPs 6 speed Allison vs the 5 speed of the gasser was enlightening. The gasser would have climbed out of the Reno basin much faster that the DP, but the DP dropped to 50 MPH on the steeper grades and never dropped below that (I suspect its how the 6 speed is programmed). When we got down to Sacramento, my wife made the comment that "this is a much better ride than the Mountain Aire" and I had to agree with her.
The ride on the gasser with Koni FSDs with great until I drove the same roads with the air ride of the DP. Much, much less rattles than with a sprung suspension. Fuel economy seems to be the same but I think the DP will give me better MPG when in the mountains. Weight difference is 22K vs 35K so I would expect some variations. I'll know more as I get some miles on the DP.