I had the HF2 and liked them, but not loved them.
I felt that they were a combination of both the RS1 and HD600 but inferior in the areas that the other do best. It didn't match the clarity, transparancy and fast raw tight sound of the RS1, so lost the fight when it came to rock, metal and vocals. It didn't match the soundstage and natural tone of the HD600 either, so lost the fight when I wanted a laid back headphone.
If I could only have one headphone, the HF2 would be on the short list and would be better than RS1 and HD600, but as a third headphone, it just didn't get any headtime. If I had to downsize I would probably go HD600+low end Grado rather than only HF2 as I need the variety.
