Looks nice!
I like the idea of using something like this across multiple systems. Whether a switch or some circuitry is needed, be well worth it as it would open up quite a larger range of potential customers.
Also, would be nice if all you needed to do was orient the controller to suit whichever preference vs. having an entirely different product to sell - that may well end up selling way fewer quantities. Some games (think maze types) play much better when you get to use your preferred hand, while shooters or beat 'em ups may be better suited for the other.