on what is essentially a 94L FSW board, that 28cm is a large-ish fin anyway.
You should not be trying to ride the fin like on a slalom / freeride / race board. You maybe need to ride the board correctly and save your $150.
If you ride it like a waveboard you will find that 28cm is too big as it starts to limit your looseness in the 'occasional slash' and you want more and more each time
The only reason to go bigger would be if you regularly use it at the lower end of it's wind range and need that little bit mor elift.
