Stumbled on this while searching for J hook rotors for my Type R Civic and thought that it was an excellent article regarding the pros and cons of the various types available and that it may help some when it comes to replacing or upgrading worn discs.
http://apradical.stillen.com/brake-technology/ap-racing-radi-cal-by-stillen
http://apradical.stillen.com/brake-technology/ap-racing-radi-cal-by-stillen