Once again, an awesome post Tyll!
It was great to finally see exactly how you get those measurements. I also think it's very interesting how only the Head Acoustic heads use the IOD EQ while all the other brands lack this new, and for many people, better EQ. HRTF's fascinate me as they change with age, gender, size of the head, shoulders and ears. So many variables!
On another note, it's nice to see my beloved HF-1's in good hands. I hope you enjoy them and I can't tell you how happy it makes me to know that you own them. :-)