I have moderate Raynaud's syndrome and my fingertips start going numb before most people's. I also don't like to kite unless I have enough dexterity to fix and adjust stuff on the water, and I'm susceptible to forearm cramp from gripping against stiff gloves or mittens. After years of trying many of the options outlined in this thread, I have arrived at my best solution yet for cold weather kiting and paddling -- a pair of mostly waterproof 2 mm neoprene gloves (I'm using Rip Curl E-bombs [ http://shop.ripcurl.com/us/shop/categor
... ess-glove/ ]but I'm sure others would work) undear an extra-larged pair of Neil Pryde open palm mittens [ http://www.inlandsea.com/p-506-neil-pry
... mitts.aspx ]. I've found the following advantages (YMMV):
1. The 4 mm of neoprene -- especially since the outer 2 mm are mittens, which tend for me to be warmer -- provide pretty good warmth down for me down to about 36 degrees F (most people are less sensitive to cold fingers than me). The fact that the gloves keep you hands pretty much completely dry helps a lot. They aren't "dry gloves", but so far they are pretty close.
2. The 2 mm gloves are VERY flexible and do not fatigue my forearms at all. The mittens, because the are open palm, also do not fatigue forearms at all.
3. The 2 mm gloves are fine for rigging the kite, tying larks heads, fiddling with quick releases, etc. You can easily put your gloved hands through the holes in the mittens to do stuff, then put the gloves back inside the mittens for more warmth.
I wish I could find a pair of 4 or 5 mm open - palm mitts to use over the gloves, but there don't seem to be any available in the US. But so far this works better for me than anything else I've tried.