Well I might have learned something.
I wasn't aware that the EPA tested engines for durability????
If this is so, there goes our govt. spending money they don't have for a task that they were not supposed to be doing.
As for the OPs question. I have the red ones. They have several thousand hours on them.
The main difference comes down to paralleling them. Not sure if the blues can still do this. I know some models have lost this feature.
But even if they can, they do have a drawback. They do not have a fuel pump, so a extended run tank cannot be used.
The reds CAN be used with a extended run tank. I made my own for about 40.00, but there are several nice premade setups available.
With 6 extra gallons of gas, I can run both at once for 36 hours!
Or if only one is needed, 72 hours!!
The blues do have the fuel shutoff, that is nice. I know of some that have modded the Hondas for this feature. Basically the on/off switch controls both the ignition and the fuel pump. A toggle switch is wired in to the fuel pump power wire. Turn off the toggle switch and the pump quits, while the Honda continues to run until the fuel is gone from the carb.
Another way is to just let it run out of gas.
Myself, I don't worry about it as I use mine a lot, so the gas never has a chance to go bad.
Both are fine units, that are quiet and reliable. Just couple of differing features between them.