Dani...
No, that's not what I'm saying. What you are referring to is the brake temp limitation for takeoff...300 degrees (or 150 degrees if the fans were running). This limitation exists relative to wheel well fires vis-a'-vis the flash point of Skydrol.
What I'm referring to is the certification for the RTO and brake effectiveness. While carbon brakes wear better when they're warm, they stop better when they're cool (or cold). The RTO certification is based on brake temps no warmer than 150 degrees.
So, in essence, you can legally take off with brakes at 300 degrees, but you may not be able to stop in the runway remaining in the event of an RTO.
Airbus has a publication "Getting to Grips with Aircraft Performance". I think all this is explained in this paper. You've probably already read it, but I think the 150 degree figure for RTOs is discussed in there.
Anyway, this is a great discussion. Thanks, as always, for your thoughtful input.
Regards,
PantLoad