I realize this thread has been quiet for a while, but I am just getting back into the forum and wanted to add my experiences.
I run a 240SX S13 in ITA in ICSCC, the regional conference here in the Pacific Northwest. I work a lot with Joe Harlan, and we have tried a few different combinations. What I have ended up liking best is the Brembo rotors (ABS) with Hawk Blue pads front and rear. This set up has excellent initial and has never faded or glazed on me.
I do not have a proportioning valve, and have never felt the need of one. All four corners' brakes are working, judging by the wear. I used to not feel like I had enough rear brake action, but after Joe fixed me up some awesome ducts for up front, and I went with the Blues on both ends, everything has seemed to come into balance very well.
One of the tracks we run is a realtively short (1.4 something) with lots of turns, and it can be a brake eater. I might throw in a set of HT-10s for use there, but I really haven't found them to be necessary.
I tried the old formulation of the HT-10s (or maybe they were HT-9s - can't recall for sure) a couple years ago before I had the super ducts. They were superior to the Blues, because they could take more heat, which was proving to be a bit much for the Blues at times. One the other hand, they REQUIRED more heat to work well. The big problem I had was that they cracked and the pad material came away from the backing plate! Joe has told me that they have been reformulated. But at this point, I simply don't need them - the Blues work so well, and the pad/rotor wear is pretty well balanced.