Having had a Yamaha 2400 and now a Honda EU2000, I can tell you from experience that the Honda is much easier if you're going to run an external tank. My Yamaha was rock solid (but it was also a 2400) and it ran all my goodies without a problem (and a Hard Start Kit), but in order to run an external tank it required a fuel pump (though you could gravity feed it if the planets are in alignment) and a voltage regulator (off the 12volt feed) a fuel pressure regulator to keep it from overflowing the bowl.
it was too much work. If I was just running it for recharging my batteries, I'd say it's perfect. For running my AC with two of them, you'll be stopping every 4 hours to refill or imagineering a fuel delivery system.
I moved to the Honda and I've never looked back.
I will say you can purchase the vacuum operated fuel pump that Honda uses and possibly integrate it into the Yamaha to get the same external tank, but again, it's more imagineering that I want to deal with at this point in my life.
YMMV
Josh