Agreed. But, I didn't mean to imply that the heat had to be excessive to damage iron rotors. Just repeated thermal cycling at temperatures developed during normal track and street conditions (age if you wish,) will set-up high material stresses, particularly around discontinuities like the cross-drilled vent holes. A brittle material will have a tendency to develop cracks whereas a ductile material will yield locally. So just inspect them.
BTW, don't take my comments to be derogatory, just cautionary. I think that ductile iron rotors are the single best change that you can make to improve your brakes.
Oh dear, as someone who recently fitted Brembo cast iron disks with P34 calipers I think I need to do some more checks.
I inspected the rotors completely when I installed them so am sure there were no visible cracks etc and I'm not a fast rider anyway but, I can forsee a question.
How can you visually tell the difference between sintered and non-sintered pads? I suspect the pads I have will no longer have any markings on them.
Finally - any recommendations for pads to use with iron disks anyone?