Not exactly STi Brembos, but I swapped a set of Endless Mini 6-pot calipers off a '02+ WRX onto the BRZ. My research was primarily focused on the equivalent systems between the GD WRX and comparible upgrades available for our cars.
Both Endless + Wilwood lists the same size caliper/caliper piston/rotor upgrades for the two cars, different part numbers but otherwise the same overall kit.
8 months and 10k street/track miles later, they still work well. Current tally is 8x track, 2x autocross, 1x drift events.
I'm about at the end of life on the current set of pads and have Winmax W5 on order.
http://www.ft86club.com/forums/showthread.php?t=49454
-alex