If you take heed of advice to try out a Shinn then at 77 kgs forget the 136 to 139. (Mark Shinn doesnt even make a 139!!)
Im around 75 & the Dundee 133 was obviously too big right from the go get. Tried the 129 as well but the 131 was the G.O.
IMO definitely the Dundee is the pick of the litter if you are riding ocean slop & doing a bit of wave riding.
On the flat &/or for more aggressive powered kiting then the Monk is the one. Again at 77kgs the overwhelming no. of kiters who have demoed have selected the 132.
Maybe go bigger if you are starting out or just like that bigger board feeling - some do?? (I just find that hard to understand).
Ive found with the Shinn boards - my experience & feedback from lots of demos - that there is almost always a clear 'right size'.
Bit like Cinderellas slipper. Its yours or its not.