I have a full brakeman kit (tornado f4 calipers, front 2pc procast rotors, 4.75" pads). The pad compounds I'm using are their #3 compound on the street (1200*f, 0.48 coef) and #84 on the track (1400*f, 0.56 coef). I don't have any ducting work on the evo, because its not needed.
If your getting fade (glazing - brake still feels firm, but you dont slow down as much), then your not using good enough pads. Cooling might help you get a bit deeper into a session with low-end pads, but you should really upgrade the pads! Look at it this way - of your gonna get your brakes over 1000*f, but the pads can only work up to 700*f, that extra air isn't going to make up the 300* difference. Ducting is a last resort, not a first. Highest cost, least impact.
When your running the highest temp pads you can justify and STILL glazing, then consider it. But before you get to that point, you'll have another problem: you'll boil your brake fluid (brake feels soft and doesn't clamp much). When you get to that point, you'll want to consider ducting (or a fluid flush if its just old/crappy).
Another thing to keep in mind is that your brakes can only work as hard as your tires. You SHOULD get the tires to lock up well before you brake hard enough to really heat up too much. Especially on street tires. Learning to do this with TC off (threshold braking) is one of the first advanced techniques you should learn on the track. I cant imagine you'd have issues with TC off. I'm able to threshold brake on Hoosier R6 racing slicks, which grip WAY harder and work the brakes way more and not overheat.
Traction control prevents you from learning this. When you brake too hard for your tires to deal with, it'll compensate by overheat your brakes (pads and fluid) with ABS. When you brake after a straight, do you feel the ABS vibrating? That's basically a motor that fully activates and releases your brake super fast. This is horrible for your brakes, and worst than that, it trains you to over-brake like crazy. If your ABS fails (which is likely if you continually depend on it), you'll probably end up skidding into a wall.
You say you like TC because it lets you 'hammer the gas better on exit'. What's happening is your rear brakes are activating as soon as you get on the gas to counter the spinning that your inducing. It might feel better, but your going slower. You should never hammer the gas, always feather it slowly. You can probably start adding gas earlier, but more lightly, then feeding in more throttle as you unwind the wheel, so your back to full throttle earlier without TC.
I don't mean to discourage your or attack what your doing. I used to do the same thing. Then when I started getting good enough to not need TC, I was already in the solo groups and was already REALLY fast, but I already learned a lot of bad habits. I ended up putting my X in a wall on a 120mph corner. People told me what I'm telling you and I didnt listen because its fun to lap (poorly driven) 911's
After my accident, I re-learned to drive on a 110hp car with no abs, power steering, tc ,etc. And I'm lapping 911's again, but with only 110hp
My lap times in a 1991 1.6L miata with over 200k miles on it are lower than they were in my evo back when I used to use TC.