You dont require V10 anymore in theory. If you havent started V11 yet just make sure you are in the right spot, route 9 I believe on V10 when you save so that you start there in V11. Other than that the only reason you would keep V10 is for side questing if you are following a guide from the forums/youtube as maps have been remodeled in V11 so it might be harder, but dont start V11 and then revert to V10.