We drive an SST100 with this very setup. As Booker said, the AC can get so cold that it can feeze you out even in the middle of the summer in the deep south. We had many times this past summer that it took some fine tuning on the thermostat to get the temp in the sleeper just right for us to be comfortable. We got to put the heater to the test this past weekend in Minneapolis. With the temps in the low 20's during the day and overnight temps in the 5 degree range. We were perfectly comfortable the whole time we were there. We got tucked away early Saturday afternoon just as the storm took hold and left Monday morning after things got nicely cleaned up. We experienced all the storm had to offer, including high winds Saturday night.
Having had most of the aformentioned generators on various trucks in the past I CAN tell you that the Onan is the BEST setup we've ever used. The Onan is BY FAR the quietest. ChetJester, get the exhaust fixed....it's VERY quiet when working correctly.
The Carrier rooftop air and the Onan generator is BY FAR the best setup we've ever had. I've yet to find the limit of it's workload. With the others we could only have one or two things working at a time. No such thing as having the AC running and making coffee or using the microwave or convection oven at the same time. This past weekend we had the heat running, made a pot roast in the oven and had the FanTastic fan going, both TV's on, the satellite on, the computer on, and of course the LARGE refridgerator all going at the same time. Not even a blip from the gen. One of the nice things about THIS Onan is that when there is no call for power it shifts to a slower idle and when it needs extra power it automatically shifts into a higher idle.
I highly recommend that you walk around a TS and listen to the various generators that are running. Talk to as many people as you can about the setup that they have and how they sound. Find someone with an Onan and stand beside it while it's running. I'm SURE you will hear the difference for yourself.