When I was making the same comparison, I got all sorts of dire warnings that the 15,000 Btu unit would not run long enough to dehumidify the air resulting in less comfort than a 13,500 Btu AC.
They all came from places like Vermont and Canada. Trust me, the 15K unit will get plenty or runtime! After living this summer with the 15K Carrier AirV, I am considering a 13.5K one. For a second air conditioner.
I have a 34’ Excella in full sun in Arkansas. elolson and I have exchanged comments following my upgrade detailed in
http://www.airforums.com/forums/f427...ead-40795.html. And yes elolson, it did eventually reach 105 with 90%+ humidity this summer here in Little Rock. I did not have to completely close off the back, but did consider it a couple of times. I got by with closing the two vents that blow towards the rear and running the vent in the bedroom. Shorts and tank tops too.
There’s a post from Pennsylvania stating what a shame someone added an AC to a great looking vintage unit in Austin:
http://www.airforums.com/forums/f48/...13707-102.html. I’ll admit it would look better without it, but that’s all it would be good for in Austin without an AC. It’s different in the South.