If you can afford the longer boat I would go with that. There are advantages and disadvantages to straight tubes vs. bananna shape. If you are going bannana I would go at least 10' because that is where you begin to see standing platforms on bananna shape hulls. I think that the only time I see a standing platform on a shorter 9' boat is when it is shaped like the Steelheader or the Bad Cat.
I have a 1 man 10' bananna tubed boat and a 12' straight tubed 2 man boat. I plan to add a platform to the 10' boat but I haven't done that yet.