Bottom End -
Using your 138 you should easily get going in 14 - 16 knts using the 132 I would say 15-17 knts. ( light wind kiting is 80% technique using the power stroke combined with the board angle etc....
Top End -
Using your 132 you should easily be able to kite up to 28+ knots
YOu can probably get going in even less than that depending on the water surface etc....... flat water is obviously much easier to build speed.
as an example :
I am about 78 -80 kg and on a 128cm board I can get going in 17knts on an 8m Switchblade 3. To do this I actually depower trim the kite slightly so if flys faster accross the wind window but it is a fine line between not enough power and the ability to generate speed.
So a 10m kite and the extra board length should negate your extra 4kg.
Having mainly used a 12m for the first 6months I had it and then trying the 10m I would strongly suggest getting the 10m . It is regarded as the sweetest kite of the range for that year .

Good luck with it