The point of these schemes is to provide you with energy at precisely those hottest/coldest parts of the year. If you want to pay more for potentially redundant backup and/or take the risk of the whole system going down, then you're only going to be more miserable.
Yes, I am aware of how these schemes are marketed. I have lived in homes that use these schemes and it's not worth it.
Maybe you live in a better climate, but not getting adequate heating or cooling when I need it most negates the entire purpose of having heating and cooling.