Any big kite in sub 12kts is going to be slow & slug-like to fly & will pull like a bulldozer when your apparent wind kicks in BUT cruising across flat glassy water (esp over coral reef etc) adds a whole new dimension to kiting.
check this out : (trying to post a pic will let you know ???)
KITESTOCK 06
17M Speed from Flysurfer was out on the glassy water while 100+ kites lay on the beach.

AWESOME.
Ian Young recorded a top speed of 40kph

(I was probably going even faster but I didnt have my Garmin on that day

)
Simon Witcherman had a demo an in just a few minutes threw a 20ft boost & hung a deadman for what seemed like forever.
All this in consistent 7 to 8 kts.
You want light wind kiting go the Speed (IMHO it the only wtg)