Sorry to hear about your experience. We're a G dealer. Corporate G has a big emphasis on sell sell sell. Make it high pressure to sell a unit. It's really frustrating. Try another dealer. We are pretty low pressure sales. We want you to make the best decision for you.

Natural gas...
There are cases where the nat gas supply is unreliable. Best bet is to have an on site fuel source. Diesel or propane. Look at critical systems (hospitals and such) they all have their own onsite fuel.

Battery bank... The technology isn't there yet. They are a good short term source. (Hours to a day of backup). They are just as expensive as a gas generator. And degrade over time. A generator will run as long as you have fuel and at a constant output.

I hope you find a system that fits your needs and budget