In over 10yrs of 'enthusiastic' driving I've only triggered mine twice, 1 of those was me deliberately being a prat on very low tread Pirellis it came with, the other time it 'may' have saved me, I'm really not sure.
I understand that TC was an option on early 996.1 C2, the C4 came with PSM as standard and at some point the PSM option replaced the TC option on the C2. (If anyone knows better I am happy to be corrected)