Common thought is that Neo mags ore ok up to 200*F... may start to weaken at like 220+ range. Depends on who you ask.
Problem is you don't know exactly how hot the rotor is in there...
My rule of thumb is 180*... over that be careful and definitely try to keep it under 200*.
I had a Feigao come off the track at 300* the other day. 
Needless to say it's a paper weight now. 