[911nut]

Originally Posted by TurboKraft

Sorry, that's not completely correct.

The rotors are 100% interchangable. They have the same OD, thickness, and rotor hat offset. The only visual difference is the 3.6T rotors have a little more cooling fin in the middle, almost like a dividing fin in the same plane as the rotor surfaces.

You are correct about the pads, however. The C2T (S4) pad is the same length as the 3.6T/993T/GTS pads, only not as tall.

I disagree.
You have to lay the rotors side by side to see the difference. The 3.6 rotor braking surface is 10 mm deeper, toward the hat section. Other than that, yes they are the same diameter, thickness and offset.
The quick way to identify the 3.3 vs the 3.6 rotor is the hole pattern on the brake surface; the 3.3 rotor has an alternating 4 hole, 3 hole pattern while the 3.6 rotor has an alternating 5 hole, 4 hole pattern.
The 3.6 rotor can be used with the 3.3 caliper and pad but if someone wants to convert to the 3.6 caliper and pads, the 10 mm of pad depth toward the hat section will hang off the braking surface of the rotor which defeats the purpose of the bigger caliper.
But don't take my word for it, ask Bill Verburg.