Ah, the myth that will not die... :S
"Does it handle any better than the 350 without a bunch of suspension add ons? "
I have owned our E-350 24' Class C for 7.5 years and 70,000+ miles. it has 3,363# of payload, 420# of torque, 305 HP, 7' of headroom throughout and it rides and handles just fine with no, none, zip, nada after market suspension add ons. Proper alignment and psi for the load it carries are all you will ever need.
As to your original question I think you can expect a lot less payload, towing capacity, storage, headroom etc. in exchange for improved mileage but then every RV is a series of compromises. Go with what will work best for your intended usage.
:C
