jamdfingr
it depends on at what wind range you are finding the 133 lt to be a hand full
anything over 20 to 22 knots with your weight you should be fine in getting an 85 to 90 ltr going comfotably
grandfromage said Narrower is the key, thats only part of it
its more the v running through the board and the rocker line that makes for comfort
I run a 90 ltr Evo which is 62.5 cm wide and the ride on that is so much softer than the 101 JP I use to have which was 61.5 wide
the main difference is the rocker line and added V in the Evo
more v equals softer ride