Thank you...would you not do it because of performance or because of longevity of a diesel engine??
As Onyrlef above says, the ride/comfort level in a gas class A is well short of the typical DP (Diesel Pusher). We had a 2010 Bounder on the F-53 chassis, and it was a decent coach, and performance was fine through the Rockies, almost as good as the two DPs I've had since, even with a Jeep toad. But long haul comfort wasn't up to either the Beaver or Ventana by quite a margin, both in cockpit noise and in comfort. That air suspension, lower CG and the much shorter rear overhang (affected by crosswinds) all contributed to greater comfort.
In addition, the hydronic heating system is (to me) worth a lot, also. Aqua Hot on the Beaver and Oasis on the Newmar Ventana provided constant hot water for as long as water/sewer had capacity -- on full hookups you could literally shower all day -- and just driving also heated the water with the boiler turned off. These systems also provide furnace heat, with individual registers (hot water heat exchanger) in various spots, MUCH quieter than RV furnaces, and including a register in the water bay set to maintain 45º F, and more even heat through the coach.
Both list the diesel boiler as the primary heat source, but both also had electric "burners" so that, except when very cold the electric was plenty when on shore power, and the diesel worked well when boondocking.
For just wondering around Colorado the gasser was fine, but for longer haul such as Denver to Baltimore or Oregon or Canada the improved comfort level of the DP left us less tired at the end of each day, and we were able to deal with very strong crosswinds that would have had us pull off and wait in the gasser.
The other side of the coin, of course, is that maintenance cost somewhat more in the DP, but not really a whole lot more, perhaps 25% or so during the year, perhaps a bit less. Of course any servicing did cost more but the need was usually less frequent.
On the Beaver (525 HP CAT C-13 engine, 50,000 lb max gross) we only got about 5.5, perhaps 6.0 mpg but in the Ventana we ranged from 8.0 to 10.4, depending on wind and terrain, cruising at 65 mph on both coaches, vs 6.5-7.5 mpg on the Bounder, also at 65 mph.
With better load capacity too, on the DPs, all the above was what made us prefer the DP. Hope this helps.