On the other hand....
Phil, I know you love your E-450, and it is rare to find one in a smaller coach, but in a Class C 24' or less it can be a bit of overkill especially if you are not towing. The E-350's 4:10 rear end gives better mileage and the softer suspension a much better ride. I give up nothing in terms of OCCC as I have 3,368#, not many, if any, 450's can top that due to their increased weight.
We have spent a lot of time at the higher elevations out here in West (AZ, UT, NM,ID, WY etc.), and our 350 climbs mountain grades without even breathing hard. Several of our favorite CG's are Canyon point 7,700', Hoyer and Hawley Lake 8,400' and Big Lake 9,200'. To reach most of these you have to get over 9,300' passes and we have been over 10,000' several times.
Most of the time 3,200 rpm (max torque), is more than enough to climb a 12 mile 6%+ grade at 50-55. It is rare that it downshifts further climbing into the 4,000rpm+ range and even then the time spent there is brief. Fully loaded we are 10,050 which leaves an additional 1,450# of available payload, though I doubt we will ever need it.
We are rated to tow 5,000# and while we probably never will it is nice to know we could. If I had anything bigger than our 24 I would definitely want the E-450 chassis but for rigs 24 or less the E-350 often can be the better choice.
As always.... Opinions and YMMV.
:C