A very technical question. I'm hoping someone with a similar setup and a spare Snow Leopard installation can help answer it. Basically I'm running OS X 10.6.8 on a late 2011 MBP 17", and I am perfectly happy without Thunderbolt Update 1.2 which is only available on Lion and above. But I need to bring the machine in for AppleCare soon, for issues that may result in a new logic board, and I'm concerned the new logic board may already have the Thunderbolt 1.2 firmware. Please, only answers concerned with my question about keeping Snow Leopard working, not anything about downgrading to a newer OS X.