The 2 different types of 17" MBP made in 2011/2012 the MC725LL/A and MD311LL/A are almost the same, the Late 2011 having a few minor upgrade tweaks, but it was shipped with Lion OSX and some people tell me that an MBP shipped with whatever OSX it has is the last OSX that you can downgrade too, back to its original OSX. I don't know how accurate this is? But the MC725LL/A was shipped with the Snow Leopard OSX. So I'm wondering since both these laptops are so close in compatibility, could you theoretically and successfully install Snow Leopard on the Late 2011/2012 MBP? Thank you in advance for your insight.