I've got a set of the Champion 1700/2000 Watt Inverter Generators with the parallel kit and was able to test run my 13.5K BTU air conditioner, microwave and coffee maker (all run independently) at about 8000'. That was only a test run to see if it would work but I haven't had both Champions long term with the parallel kit as I just bought the second one. I bought my original Champion 1700/200 3 years ago.
BTW, keep an eye on pricing at Cabelas as every so often they have an unbeatable price with free shipping (I purchased about 1 1/2 months ago for $399). I was also able to get the parallel kit on amazon for an unbelievably low price of $18, prime shipping around the same time.
I do like that the Champion 1700/2000 gens only weigh about 50lbs each which makes loading them a lot easier than a 100lbs single unit.
EDIT: fixed a watts inaccuracy I originally posted. For some reason Cabelas is listing 1600/2000 but Champion's website says 1700/2000. Amazon pricing is currently $439 for the single inverter generator.