A $329 4000 watt Champion generator will power anything and more that the Honda will BUT:
-Is much louder, the Champion is as loud as a shop vac. The Honda is super quiet, and engine speed varies with load so at no load it is near silent
-As you mentioned, the Honda will use much less fuel at lower loads.
-Service, the Honda comes with a 3 year commercial warranty, and you can get it fixed at just about any Honda dealership
-Weight/size, the Honda is small and light, you can practice arm curls with it. Any 5000w unit is going to be a back breaker.