I got an old board I was planning on...
I got an old board I was planning on splitting, but it has a very soft flex. Will this still work ok, or should I look for a stiffer board?
As a general rule of thumb, a stiffer board will be more effective in powdery conditions. If your board is park/jib specific, you might consider using a different one as a split board. But, if you have no other use for the board and it will just be collecting dust sitting in the back of your closet anyway, what will it hurt to try? It might work for you and will definitely be cheaper than buying a whole new board.