do what i have done and have both. c4 in medium size and cat in smaller size. it works great.
you can get the fun of that punch and dynamicness in the good conditions and then when conditions get worse/windier switch to the cat.
infact i do the full sweep of the ozone range
13m edge, 10m c4, 8m cat, 6m reo
takes 30 mins or so to dial into each kite. but once dialled... mmmh
edge gives me great upwind and awesome glide and float in light winds.
c4 provides the punch.
cat big grins in silly winds
reo. stupid swell and storm kiting