I really appreciate all the responses! One of the Delta 2 Max features is "AC Always On" so that is definitely what I need. I see that the Anker SOLIX F2000 has a UPS feature with < 20ms switch time (although I would prefer an "AC Always On" feature). Any objections to the Anker SOLIX F2000? What about OUPES Mega 3? The Delta 2 Max is a great product, I'm just exploring different options.