I was advised that since your current coach has Coleman you might want to stick with them. There is a good possibility if you go with another company you will need to change out the thermostat as well as wiring and modifying the new thermostat to work with the shedding, or auto-start generator etc. Also check out the roof opening to make sure the new companies air conditioner will fit with the hole and brackets.
If you do go with a different brnd, make sure you check back here and let me know how it goes. I'm wanting to upgrade the original units also.