First of all, I would never run the standard pads in the front. I'm going to run R4-S up there no matter what.
I've run my car on track several times and I know the value of good pads. I used to run Hawk HPS up front, but the rotors just weren't good enough to keep the temps down. I always had standard Raybestos shoes in the back too. They never really got hot. This 240SX setup is still 10x better than my old drums no matter what pads I run. It can't be worse than it was before!
I realize that brake proportioning via friction materials is less than ideal, but I am on a budget and my rebuilt 240SX calipers came loaded with normal pads.
Frankly, I probably will just bite the bullet and pay $60 + $40 for the prop valve, but I don't really want to.