The hill assist cannot be disabled on the WRX, only STI.
And if you say we're wrong again, you come down here and I'll watch you try to disable it on mine.
And it is not a nice feature... maybe if I had a switch to turn it on or off you could argue it's a nice feature, but having it forced on 100% of the time does more harm than good.
I'm going to get the factory service manual and see what it says. If I can get the schematic for it, or at least some more info on where the thing that pulls the parking brake is, I'll get it disabled one way or another.