Well I deliberately called my tool "Hajo's Headphone Enhancer" because it is optimized for my head / ear sizes ... that is (in my opinion) also the biggest prob

Well I deliberately called my tool "Hajo's Headphone Enhancer" because it is optimized for my head / ear sizes ... that is (in my opinion) also the biggest problem with measuring actual HRTFs with dummy heads: It'll only work if the user has a head that is similar to the dummy head used for recording.