I am considering setting a firmware password on my Retina MacBook Pro for security reasons. If I do this and later lose the password (or other such extenuating circumstances), how can the data be recovered? Is it even possible?
It is possible for the lost firmware password to be reset, but not by a normal user. As an Apple Certified Macintosh Technician working for a third-party service centre, if someone brings in a machine that has RAM soldered to the Logic Board and they have forgotten their firmware password, I can upload the serial number and request a firmware password reset. We're then provided with a disk image that can reset the firmware on the machine with that specific serial number. I believe, but can't confirm at this stage, that the utility on the disk image may expire after a certain length of time.
For all those concerned about privacy, any technician that requests a firmware password reset will have their details logged on Apple's end — so if it's reset for nefarious purposes, the details about which technician performed the reset can be tracked down quickly. The reset also requires direct, physical access to the machine - the password cannot be reset remotely.