Hi Tolga, with your weight, I would really consider the wider board, for a bit of extra stiffness and stability - the Isups generally need to be a bit wider vs hard boards, as they have no hard rails, so this already makes them less stable. And the thickness means they "float" on top of the water, vs the hardboards which sink deeper into the water and create a certain locked in feel? Are you sure you want to move to an Isup, rather not trying a new Strike BXF for example? The 25" is probably easily as stable as your current 26.5" Fly?