There is no best practice for migrating from one theme to other. Generally Office_Black, Office_Blue and Office_Silver are all color variations (for all telerik controls) which means only the SolidColorBrush, GradientColorBrush and some Thickness and ImageSource resources vary. You should be able easily change the color resources from one of these themes to the other. However Windows7 for example will expose different ControlTemplates and eventually different names for the color resources so changes will not be so easily exchanged.
The good news is RadScheduleView is relatively new control so all themes are color variations for it at that moment. However that may change in future. Also we does some development on it so you may have to upgrade your ControlTemplates with new releases in order to get the new features working. We avoid backward compatability issues as much as possible.
the Telerik team
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