Hard to say how much power the dry sump is worth. Kind of depends what you compare it to. There are a lot of advantages that come with a dry sump which are difficult (and expensive) to duplicate with a wet sump system.

This dry sump pan is super big. It was custom built to be as big as possible and still fit on the dyno stand. The last dry sump pan that I had was big, but this one is probably twice a large as that one. The extra volume probably helped make power but we didn't run an A-B-A test sequence. That sort of testing is best performed when you have a $15 an hour shop rat who climbs under the engine and changes the pan while you go to lunch!