Having just recently invested in a DP I sympathize with your observations. I am wondering if mine needs more caster, if it was not so far to the nearest Freightliner dealer I would have taken it there already. I was also disappointed in how it handles sharp bumps in the road. I agree with the comment about the front door but must say that is why I picked one with a mid-door which I really like. The things I like best about the air suspension are that I can lower it when stopped and it always rides level.
As the owner of an E350 with a V10 I feel that my 300hp diesel is more powerful but the coach is definately heavier so they accelerate about the same when loaded. However, the DP gives about the same mileage as the van and I get to take a lot more with me. It also seems to be much less affected by a trailer.
The coach is quite for the driver but the bedroom is noisy. I wonder if that if that was a good swap.
I have a Palazzo and just looked at a friend's Outlaw gasser by the same manufacturer. Each has things that I like and things that I don't. To that point there are things I like about backpacking, the old popup I had and the truck camper that I still need to sell. You just have to pick the rig that fits your needs best right now.