Dual Booting to get at a different OS is difficult enough on Desktop as far as I'm concerned. It would leave you so fragmented that you just couldn't be productive. Might be okay for a teenager that has no real work to do.
As far as flagships like that coming with an "option" for one OS or the other, that would be okay. Samsung Galaxy W10 version and Android version, but not dual boot. Perhaps even an option where both are installed, and when you boot up the first time, you can "choose" which one you want and it will delete the other. Would need software buttons instead of hardware buttons, though.