pnichols,
It sounds like you stumbled on "That Perfect Unit" for you as did us. That is a very sweet place to be. I know what you mean about a list that can be written down about all the great reasons that make it so. Like you say, our slimmer PC is has it's benefits until parked, but we manage well with the tighter quarters. Our PC is nearly shoe-horned into our garage which is a "personal" benefit.
About our E350 with slight rear end sag. The fresh water tank is in the worst possible place with consideration to weight distribution. It is right above the rear bumper, passenger side corner. We like to travel with it full which creates the condition. A year or two later, Phoenix relocated the fresh water tank in our model, placing it more forward and more centered in between the rear tires. That made a difference in weight distribution and rear end sag, but I feel at a notable sacrifice to the under-bed outside storage compartment. Everything has it's trade-offs.
Where is our dinette, refrigerator, generator, propane tank, and several outside storage cabinets located in our PC? With exception to the outside storage compartment they are all between the axles. I pay attention to what is kept in our outside storage, it primarily stores our barbeque grill, many sacks of lynx blocks, and other light weight bulk.