Having owned both, the first an American conversion (1985) with Prevost bus air and heat with 3 cruise air units. The second coach, a 1995 Vision with no bus air and heat. The current coach, (95 Vision) has dash air, and 4 roof airs, which is capable of operating the front and rear roof airs from inverters. It has 2 3,600 watt inverters operating from 2 banks of 8-D batteries. (a total of 8 8-D batteries for the house side).
So far, it works ........ok with this system. I fell for the old story of (A) it saves bay space , where do you think the batteries and inverters are housed?..in the saved bay space of course. (B) It is more efficient because it does not sap the engine hp to operate the a/c. ..Where do you think the power comes from which operates the alternator which supplies power to the batteries thru the inverters to operate the a/c units....from the engine!. and (C) why do you think most all of the converters do not build coaches with prevost road air and heat?....Because it is cheaper!
Having owned both, I would not buy another without PREVOST BUS AIR & HEAT..

It is much easier to manage, just turn it on as you would in your automobile, adjust the temperature control and you are good to go!

Also, if you should loose your bus air and heat for some reason..start the genset and run your roof or cruise airs. Or a Jon stated above if you are trying to cool a hot coach prior to a trip run both systems for a few minutes to cool the coach for travel, then shut down the genset and use the bus air and heat.

I have heard these arguments pro and con for years, but if you travel in the hot regions of this United States, you need Prevost Bus Air and Heat. Just ask someone who has owned both!

Now having said that, those of us who do not own a coach with Prevost Bus Air & Heat should not get rid of our coaches, we should just contend with batteries/inverters, or run our gensets, roof airs or cruise airs, our dash airs
and not be quite as comfortable. (maybe change our shirts before we arrive so as to not have sweaty armpits, and look as though we have traveled in comfort to our destination).

Its really not all that bad, just trying to make my point on the ease of operating a prevost with bus air.