I'm hoping someone can help, I've read different things about upgrading the SSD in mid 2015 MBP Retina 15". I need to upgrade the SDD to 1TB and the only option I can find (in Oz) is an OWC unit that costs close $1K. Are there other options available? I did read a post that in the newer MBPs the SSD interface was proprietary Apple and upgrades were difficult. I have no idea if that's true or not. Thanks for any help.