Wheelbase length is but one factor in ride quality. In general, the longer the wheel base, the smoother the ride, but there is no length at which ride becomes good or bad. Other major factors vs an F53 gas chassis is air suspension vs spring and rear power vs front. And if you were talking about an older F53, say before 2005, any DP probably has a structurally stiffer chassis as well. Your '07 should be fairly good in that regard, though.
Another somewhat nebulous factor is the quality of the motorhome itself. DPs in general are higher priced models and part of that higher price is more care lavished on noise reduction, insulation, vibration, etc. But a larger DP is an even more expensive model and often has even greater attention to those factors. How well Damon did on noise reduction, etc., is something I can't comment on, but some builders do better than others. It is also possible that Damon skimped a bit on your particular chassis, going on the small side to keep costs down to a minimum.