The whole thing is an urban myth! The original SC2 V1.05, the V1.07 and the SC2.2 all had exactly the same attack and release characteristics…. they had the same components in the compression circuits. The only differences were alterations to circuit layout and the revised output stage. It was always possible to get the same sound out of all three models. It’s possible that some were made with fractional changes to the internal gain structure, but you could (and still can) get the same sounds out of all of them.
Units after the SC2.2 had changes, but even then, I still say it’s possible to make them sound the same.
The TFPRO compressors use a number of different circuits; the attack structure is more controlled, but it’s modelled on the old originals, the LA2A, the Altec and the Urie.
Personally, I think the original type of optical compressor is the best of the lot…. in modern mixing to get best level you sometimes have to follow it with a plug-in limiter, but that works OK and doesn’t destroy the sound! 😯
Drop me an email on email@example.com and I will email you the circuits for the V1.05 and the SC2.2 (the 1.07 was just a re-laid-out 1.05).