Grandpa, very high quality review, though I wished you had also owned either a Tiffin or Newmar dp as part of your experiences for comparison purposes.
My basic premise, not necessarily one that others would agree with, is that if the chassis is satisfactory, the house is secondary. The reason is that as far as I'm concerned a tremendous amount of changes can be made to the house to make it work. So, when I look at your list, basically, I personally rate the issues as "no big deal."
For example, if you can afford to buy a Seneca, you can afford to drop off the entry level tv to Goodwill and go out and buy a high quality tv. And, yes, I feel like all the rest of your issues are as easily dealt with.
But that is why I would buy used, and for (me) the top 5 issues are chassis, chassis, chassis, chassis, and chassis.
After I retired, the first "buy" I made was RV service technician training, my second is my Boxer dog, my third will be Trike flying lessons, and then maybe...