I myself in the past have inadvertently wasted nuts (doughnuts) purchasing energy or some other such thing only to find that the system closes and goes into a update, I doubt I am the only one to experience this.
I for one would appreciate a warning message prior an update, even if it is only an in-game message to inform us that the game will be un-accessable in the last hour or so before server refresh/reset.
Thank you,
ATR