I had a 16,000 BTU installed in my 05 37PC last year, in the rear starboard hatch, with outlets in the rear, and three 3" outlets at the helm. I feel it works great! Of course in the middle of a 95 degree day it only pulls it down to about 78-82 degrees, but it also pulls out the humidity, so that temp feel pretty good. And evening and nights are awesome if it's too humid, buggy or rainy to have the canvas down. We've ran all day "buttoned up" on hot, humid days doing 125 miles with the generator running both the cabin and cockpit AC's. The two units do cross cool, so you have a combined 32,000 BTU's.
And we were surprised to see how much we use the included cockpit heat for spring, fall or just in the morning to defog the windows/canvas or take out the humidity before running. Simply put, it was the best boat dollars I even spent. With cockpit AC/heat you can invite guests anytime without worrying about the weather, because you can control the enviroment if needed. And my buddy had the same unit installed in his 08 40 PC, with the same satisfied results. I would install cockpit AC on any boat if possible. Of course 32,000 BTU's would be great, but if 16K is all you can do, it's still well worth it... IMO!