Redwood. It's good to see that you were able to get the info that sisyphus needed via the internet. It has been and still is common practice in my area to offer an additional anode installation, if the tank allows it, as part of extending the life of the tank. You may still find manufacturers installing additional anodes, as I have mentioned, which is good to know for future maintenance on the tank.
I am a bit puzzled by the conflict of info given to sisyphus by you. You stated that there is no difference, but the price, on long warranty or short warranty tanks yet the info posted from GE shows that there is a difference in the anode. There is additional info that GE provided that reflects the cost difference between tanks. Not just an insurance policy, but some people want to pay more for better elements, brass drains, lined tanks and heavy duty anodes.
It was assumed that the tank was electric, but may be gas. If the tank is gas, it would definitely benefit sisyphus to flush the tank instead of waiting for the next new one. The tank will heat more efficiently without a build up of sediment and will also remove a potential breeding ground for bacteria. An anode change could add years to the tank, depending on its current condition.
You might be surprised how happy a customer can be with your services once you offer a little more than the norm.