We have a 2002 450 PSD. It does ride more like a truck than a car. We had a 250 before we got the 450 so we have a really good comparison. It is very "stiff". When towing the ride is much better and it is hard to tell the difference between the two trucks ridewise.
As for the gearing. We have the 4.88 and I thought I'd have a much lower MPG than I had with the 3.73. This has NOT been the case. I am getting about the same MPG as with the 250. With the added benefit of much stronger pulling and stopping power with the 450. I have not had one of the newer pickups with the tow/haul feature but with the 450 and the 4.88 gears I believe it "acts" much the same. With the 250 I could not use the cruise control except on flat or downhill terrain. With the 450 I can use the cruise control almost all the time. Only on the really steep hills do I have to drop out of cruise.
So ridewise the 450 is rougher. MPG wise my experience is that there is not much difference.
The dually does not stop us from going and seeing anything we have wanted. We do not garage the truck so that is not an issue. The truck is huge so we do have to look for very large or "double" parking spaces. This is inconvenient sometimes it has not been a deterrent.
Get the tow vehicle that works for you. My "dream" vehicle is a big rig like FireTrucker has!
Good luck with whatever you get.
HamRad