No doubt the out of camera images from a FX camera are fantastic and give you so much to work with in editing.
Without a doubt the Tokina 10-17mm goes into the Underwater Hall of Fame. I owned two, on had the 1.4 teleconverter on it and never came off.
A well respected person with one of the top housing manufactures told me "National Geographic will take images from a point and shoot as long as it is of something amazing and in focus. Taken with a grain of salt, but that always stuck with me.
Of course Alex is so right, but here starts the slippery slope with DSLRS. When I use to work with people I always told them no use buying a Porsche if you are going to put tricycle tires on it.