I see what you mean now.
You're doubting between 2 totally different boards.
JP X-C145m, width=76cm
The JP X-cite is more a bump & jump board. Out of my last summer's experience, it are very nice boards, very good all-rounders and very easy to ride on a choppy/wavy sea like in Rhodes or the Baltic sea. Actually it's something that SB does not really have in its range. I compare it more with a Kode, which SB does not have bigger than a K123.
I've never sailed an IS144, but I think it will be a much harder ride on chop.
On the other hand, when you're looking more for speed and sail most of the time on your lake, it can also be appealing
Perhaps you should think Futura, it will be something in the middle.
As a SB fan, I would know what to choose though