They are interchangeable provided you get ones that are Third party knock offs don't usually include the smart circuits to ensure they don't melt down. Unless you are sure it will work on both use caution or expect there may be some issues. This has already happened with some people who tried cheap car chargers on the Pro only to have them melt even though they said they were for the Pro. Fortunately those people were more interested in the charging tip than the actual charger so it wasn't a huge loss. The seller quickly changed the compatibility but it just shows you never know.
I've had mine since the beginning of April (see earlier post). I charge my SP every day for 8 hours while I'm at work and have not had an issue. Just sharing my real world experience.