I did not test two wheel, because I got donated a very large motor. It worked well, so its still running strong years later. I don't know if it is better running 2000w through it vs two 1000w motors. I only know that I could load up to 450 pounds total weight with that big 25 pound rear motor. ( an old crystalyte 5000 series) Never had a bit of problem with traction, but I could say two wheel might be better for paved.
Others have done two motors, two DD's two geared motors, etc. All report great ability to climb with heavy load, as it should be. All would be capable of 1000w per motor. 2000w will get you over the rocky mountains, allowing 15 mph up typical grades of 8%.
Let me just say I don't know the xionga. but ALL hub motors suffer the same fate, you cannot overload them, and have them perform cool. Don't be fooled by low load rpm heating data. Listen to those of us who went out and deliberately melted motors testing them to destruction. You will be overloading them, if a hill is 5% or more, and several miles long. I assure you this is true, even of the mid size DD motors.
Again, two of those xionga's gets you double the power, increasing your rpm up a hill heavily loaded. Then you can load up, with double the motor. Whatever works for you will be fine, you just need to avoid overloading a hub motor, one way or the other. My philosophy for touring had to take into account that I live in desert, so to ride across desert, and then over the mountain, I had to have a motor that absolutely never overheated, despite 450 pounds of load. Break down in the desert no problem, its only death. So one big reliable motor, two smaller reliable motors, whatever.
Or mid drive.