16 GB installed and operational in my late 2012. However, I had 16 GB running in my mid 2010 as well, which Apple lists as maxed at 8 GB.

I have the same drive. No way to easily disconnect the drive from the USB wiring. I expected a PATA or SATA connection. If anyone finds a way to use another type of USB cable (or FireWire) to connect a replacement DVD or Blu-ray drive, I'd love to see it.