I've got mine cooking now. I'll listen to them every 12 hours or so and see if they've changed at all. I figure 50 hours will be enough for me and then I just plan to listen and not mess around with the break in anymore. Just let it happen naturally.
Because all of my experience is with full sized hp's, I find myself wanted to compare the gr07 to a pair of full sized cans. The closest that I've come up with so far for comparative sound signature is interestingly the hd650. Just an observation.
Looks like that I got in the game too late as this thread seems to be inactive now. Oh well, there is lots of material to read through.
The older MKI(-2?) comes closer to the (darker) HD650 sound than the MKII I believe most who've heard both will agree.