Well, if you had a completely stock car with only 17" wheels and tires, you would want to use a more aggressive pad up front. From a pure friction standpoint, you never want to use a street performance pad on the front of your car on the track. In the rear, you can usually get away with it unless you're running sticky tires and you're really driving the car well. It's so easy to change pads with our calipers, I don't understand why people make such a huge deal out of it. Is it so bad that you would rather have to babyfoot your way around the track with an $1800 brake kit on your car, or would you rather take the 30 minutes to swap in track pads, bed them in, and go out brake everyone else on the track?
Of course you're going to get into the argument of "If I spend that much on a brake it, it should work flawlessly wherever and however I choose to use it." Unfortunately, that's not the case. You could go out and spend $10,000 on the kickass Brembo four wheel kit that's on the Sparco EVO, but you would still be frying high performance street pads at the track. I kid you not.
The fact of the matter is that current friction technology cannot create a pad that:
1. Is totally silent. (Think of the reputation a noisy pad gets on a message board)
2. Doesn't dust. (Think of the reputation that a dusty pad gets on a message board)
3. Has good cold friction. (Think of the lawyers coming to take away your house because the pad you sold as a street pad didn't stop Joe's car first thing in the morning and he plowed into a mother pushing her twins across the street)
4. Is easy on rotors.
5. Leaves rotors perfectly smooth and mirror-polished.
6. Has good pad life.
7. Does not require the "customer service nightmare inducing" bed-in process.
8. Has a stable torque curve.
9. Fades gradually rather than torque falling off quickly(mid-stop).
10. Has good release and modulation characteristics.
11. Has an MOT that will allow aggressive track use.
12. Does not deposit uneven pad material when overheated.
13. Isn't too expensive.
14. Is available in your pad shape.
I apologize if that was a bit too "tongue in cheek," but hopefully it helps people understand just how difficult it is for friction manufacturers to produce the "perfect pad" that we're all looking for. Now that I'm completely off topic, I'll say goodbye.