The recipe looks like it will be a tasty beverage. I would think about swapping around to FWH, vice doing so many dry hopping. Just my .02. Overall, I can't wait to hear how it turns out.
Its all about surface area of the component of the heat exchanger. In the case of a counter flow cooler, the outside of the cooler is were the water (cold) is flowing, and the inside is where the beer (hot) is flowing. All things being equal the larger the surface area that the cold (water)...