I've heard and loved most of the classic Grados . I've owned every pink driver model (RS1, SR325, SR100/200/300) and find they represent my favorite John Grado sound, but I always ended up selling them on. Then I found these weird things:
These have the smaller red/pink drivers found on John's earliest headphones, and HP1000 gimbals. The cups are very shallow, about the same depth as early SR60s, and as a result they don't fit in the gimbals properly. You have to insert them "backwards" to get the angle right when they're on your head, but it doesn't negatively effect the comfort.
They sound phenomenal. Similar to the earliest RS1, but they're designed to be worn with flats. The inscription on the buttons matches that of the prototype RS1s given to dealers, but I've never seen the cup style used anywhere else. All in all, I'm smitten. Loans available on request to SO.