Ive gained lots of experience from flying in the RHS with other more experienced PPL's. It is an oppourtunity if the commander is happy to do the Radio or Nav etc, as long as the commander is happy for you to do that and he is at all times PIC especially on a Commercial flight of any description. If the chance is there go for it, biut dont expect too much from it and certainly dont pay anything for the flight(s).