Hi Eric b 125,
The definiition for "light wind" probably differs as you travel around.
If you live in a truly light wind area, where the wind rarely exceeds 20 knots, light wind is anyting < 14 knots (say 8-13 knots).
Below 8 knots, not many boards can plane, even with => 10.0 m2 sails.
So "light wind" probably somewherein the 10-12 knot range.
If you live in a very wind place, with windspeeds over 20 knots much of the time, light winds might be defined as 15-20 knots.
If you have 10+ knots of wind, you are probably in a "light wind" area and the larger 144
(with a larger fin and a => 9.0 m2 rig) Tecnora board may give you alot more planing time.
If your winds are above 14 knots, then the difference would begin to favor the 133.
Unfortunately you are not a "lightweight" so wider boards, larger fins and sails will be what your need to get the max planing time with the windspeeds you suggest.
Hope this helps,