I think you should go with the smaller board.
I did start out on a larger board, but just as soon as I got a grasp on things, a smaller board would have been better.
I'm still using my Slingshot Dwarfcraft, which was my second board.
I think maybe the exo board is comparable.
It might be a bit harder just starting out, but you won't outgrow it to the point that you quickly wish for something smaller.
Also, I'm about 83 kg, and slow and clumsy.
When you start out, you don't want to be milking the kite to ride at the lowest possible wind speed.
You want enough power where the kite is still easy to fly, and lifting enough where maybe you can go really slow and use the kite as a crutch if you need to: this is way less wind than what it takes to go up wind on a twintip.
If you find yourself getting up, but then wacky out control, then you need to try a smaller kite.