I have the EF6300iSDE. Kick ass unit. Yamaha is as good as it gets. THE best. I'd rate Honda a close second, but you can't go wrong with either one.
Mine sips gas - it's amazing! Only has a 4.5 gallon tank. I ran it for 5 hours during the last outage, & the gas gauge didn't even move! It's crazy! Carbureted too. Sometimes it sits for close to a year before I remember to test run it ... and it always starts right up after the fuel gets to the bowl. After each use I pull the panel & drain the carb., so that helps keep it reliable. Has all the treehugger BS on it which probably keeps the fuel fresh in the tank longer. One benefit of that I guess ...
Has a efficiency setting that sets the engine RPM according to the load. It's not real good with big loads - like when a big electric motor kicks on - but it works. I just let it run full tilt until everything in the house has settled, then turn that eco setting on. Crazy how little fuel it uses on that setting. Makes the well pump & oil burner struggle for a second or 2 until it ramps up the RPM's.
Also this is the quietest gen set I have ever heard in my life. When this thing is running full tilt in my greenhouse, you can't even hear it 100' away. Has a car-sized muffler in there - seriously!
The only thing I don't like about it is the safety stuff - namely the GFCI outlets, which trip at the slightest fault. That's good for most, but not when I try to backfeed my barn. I tried everything, but the damn thing trips every time. I painstakingly separated all the neutrals & grounds in the box, & still no luck. I was able to cheat it by eliminating all the grounds in the plugs I wanted to run. But that was a pain in the ass.
I expect to have this thing for years. I own several Yamaha motorcycles, & they all run forever.