Or, to just answer the question, yes. Yes you can go on ANY Brighton and Hove bus with the Smart Saver. I have done it. Merrily, in fact.
And in other bus news, those old Stagecoach plodders on the 27 have been sold, and are going. The buses which were on the 5s before the new fleet arrived are being painted the light blue of the 27 livery.