I used to own both C4 and Vegas at the same time both 2011 both same size 9. I would almost 90% at a time naturally reach for the Vegas when going to the beach.
My chart:
Vegas: Boosting 10

, Loop 8, Unhooked 9, Stability 10, hangtime 9, Bar Pressure Med light.
C4 : Boosting 6, Loop 8, Unhooked 7, Stability 8, hangtime 6, Bar pressure Med light
If I was to buy one now i would also consider RRD obsession 9. I have one now it is very sweet kite. Landing my all my loops with nothing to it.
RRD Obsession : Boosting 10, Loop 10+

, Unhooked 9, Stability 9, hangtime 9, Bar pressure light
Hope this review helps. good luck!