A GSP will not take more training; you will just be focusing on different issues than you would with a Setter.

I think you'll end up with a GSP, but you might want to look into getting one that comes from a breeder who follows the German breeding methodology. With all the damage that the AKC has done to the GSP, unless you already know the breeder you want to work with, finding a good DK that has the greatest probability of meeting your expectations is going to be much easier than getting a GSP.