Thank all, picked up a Predator 4000 today. Couldn't pass it up since it went on a 3-day sale for $279 and the local HF had them in stock. Pretty heavy compared to the inverter (128 pounds dry), but I expected that. Wheel kit took some figuring out, I thought they had shorted me 4 nuts but it turns out there are captive nuts on the frame that the instructions don't mention, and they don't mention what to do with the 2 extra washers; figured out they go in the rubber feet so the bolts don't pull through. Oiled it, gassed it, and it fired up on the first pull. Ran it for an hour with a 500 watt halogen lamp. Definitely louder than the inverter, but I discovered some of the noise is the plastic control panel vibrating against the gas tank. Maybe some foam weather strip material would dampen that. Figure I'll break it in on the GTX 10W-30 I had and run Rotella 5W-40 after a few hours.
Thanks for the tips on turning off the fuel valve; I've always done that on the inverter but it's still a pain to start even with Sta-bil in the tank. I think the auto choke is its biggest headache, I have to hold it closed when starting which means opening the case. Closing the fuel valve on the Predator makes the float bowl dry, I didn't get anything out of it when I opened the drain.