i have just cracked a dba 4000 at the track and looked into new rotors.
RDA for the road and light track work (have a look in the group buy section, i had no problems with these)
DBA 4000 for the same purpose of as above, but cost more....will crack under prolonged heat (from experience)
DBA 5000 are two piece, better cooling, lighter, cheap end of the 2 piece rotors, double the price of the 4000 and well over 3 times the price of RDA
Project Mu 2 piece, almost double the price of 5000, more of a track rotor
brembo, harrop etc, didnt even look into
i bought the dba 5000, two track days later, they seem fine.