On my 609, I had SD7 arms, with SD7 lever and Clarks cable. Used with snowies, heatsink yellows, TNN greens... Few more like... Very average brake. Could never really get it snappy, though that may have been the lack of setting up skills. Anyway... Today, I switched the arms to some cheap ass "Promax" arms and a wilko's cable, out of sheer desperation. Oh. My. GOD. It's f**king amazing. Grabs like CRAZY, but still modulates, because it's a Vee. (This is with Phat pads on a grind.) Probably just old, shit springs in the SD7 arms, but I'm more than happy to downgrade to these Promax things. It's unbelievable how much better they are. I would recommend one, for sure.