It is hard to resist the allure of a new ski once you have begun to lust after it. I have given in many times.
Let me throw a little ice on things. With 11kph race speed you are an intermediate paddler like most of us. As bartons numbers demonstrate, speed gains between boat classes are not huge at intermediate speeds. This is because of the trade off with stability of course, but also has to do with the relative contribution of friction vs wave generation to boat drag at different speeds. At any rate if there is not a huge difference between boat classes at intermediate speeds then there is probably almost no difference in speed within boat classes at your speed. i suspect that any slight difference in hull speed between the various elite hulls would be dwarfed by the differences you will find in comfort and ergonomics between the various skis. So if you are going to trade to a different ski, make sure that it feels more comfortable and more powerful to paddle than your old ski, otherwise It is probably not worth it.
Probably the right answer is to take the money you would have spent on a new ski and spend it on coaching and training. That will get you more speed than a slightly different hull i think. Mind you I have never made that wise decision and hired proper training myself, but it is probably the right thing to do.
Current Skis: Nelo Vanquish AIR, NK 670 double, NK exrcize, Carbonology Feather, Think Jet, Knysna Sonic X
Former Skis: Epic v10g3, Kai Waa Vega, Epic V12 g2, Epic V12 g1, Epic v10 double, Nelo 550 g2, Fenn Elite S, Custom Kayaks Synergy