I have a 24' Lazy Daze on E450 w/V10. The weight is in the mid 10,000 pound range.
To me the chassis does not feel over sized at all. I installed beefier anti sway bars and a track bar to firm up the handling. I still have the Ford shocks, but at times they feel a bit sloppy.
Ride in the front seats is pretty good-for me not an issue. As mentioned some impact harshness. This could be from stiff sidewalls and high tire pressure as much as anything.
FWIW I would not want any taller gearing in the differential. To me it feels just right as is.
