While I respect your view on Generator sizes,
most smaller units (Honda's excepted) don't last long.
Change the oil on a regular basis and especially after the first 3 to 5 hours of use.
Use Stabil or equivalent fuel stabilizer.
Lacquer is no fun to keen out of a carburetor etc.
Also fuel consumption is less true than claimed by advertising.
The fuel math is a little jaded too.
You will burn the fuel equal to your power setting (load).
What you seem to be saying is that the minimum fuel use (or flow rate floor) is higher in larger generators, but that's not really true.
More or less you will consume fuel based on the power consumption. The difference in fuel efficiently isn't like an automobile where the large car weights more than the compact.
Also remember that the performance ratings are not really continuous duty unless the generator is name plated as such.
It's nice to have some head room in capacity, you never know what you are going to run into or need.
Fuel can still be saved if necessary by just running the generator on & off time as a 1 hour on 1 hour off for most things (like fridges, microwaves etc).
The bigger generators also typically regulate better and have more stability and reduced electrical noise (but not always acoustical noise of course) You can build/buy an enclosure to reduce acoustical noise.
One final thought, mark your calendar or set an appointment, but run the generator once a month for at least a little while.
We have a number of gen-set both personally and at work.
Many has been the time when someone tried to fire up a generator for an emergency (unexpected need) and couldn't.
Good luck.