I think the 21 Nemi is about as much pull as you need (see below) IMO, get a better board (if possible). I can't express how much I believe that the board is more important than a kite (tenfold)

Dr. Shane was recently on his 23m Contra and his 157 UG WT (around 190 lbs.)
He was holding ground, doing okay.
He then came in, hopped on Dr. Bruce's 15m Fuel and switched to my Magic Carpet (for half hour) and then to the Barn Door by Aggression (for half hour). He was screaming upwind and jumping on the Barn Door and doing real well on the MC.
I can ride the barn door on a 15m (in 11) much better than having a 23m kite and so-so board in 13, that simple.

Its obvious to me the place to put the cash is in a great light wind board.
I have seen over and over and over, ad naseum the effect of a great light wind board in marginal winds.
I would keep the kite, and buy that guy's MC off of ikan't.
You will never regret having a killer light wind board, trust me.
BTW, the Barn Door by Aggression is unreal (better than the MC, IMO)