You can often get a second life out of a set of OE rotors with new pads, but why would you if you are concerned about performance? Less thermal mass just means they will fade sooner. Go with new OE.

You ask about rotor specs and metallurgy, but IMO the most important spec is cooling performance, relating to cooling fin design. I wouldn't expect knock off rotors to match OE performance in that respect. And nobody publishes performance specs.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue