Hi m8,
As has already been said there is no advantage to fitting another d/valve other than noise
I have had 2 baileys piston d/valves on mine and both leaked, i have now fitted a turbosmart vee port valve and it doesnt leak and sounds good without being too noisey, its easily adjustable too.
If you do fit a vta d/valve i would change the oil quite frequently with a good quality oil, i have mine changed every 3000miles with motul and dont have any problems with oil/fuel mixing.