>And to respond to your specific point - I'm not clear on how a new blank drive would be a security concern. There might be a technical reason why it has to be

>And to respond to your specific point - I'm not clear on how a new blank drive would be a security concern. There might be a technical reason why it has to be this way - or it could just be poor design. At this stage I'm curious to know the thinking behind this. The Apple security guide spells it out but I can hopefully summarize: the firmware for the T2 is stored on the the SSD, and it gets signed with hardware keys present in the T2 itself so the system can know if it's code is intact or has been modified. If you remove the existing SSD and install a new one, there is no longer any T2 firmware present. Without it, the T2 can't start and since the T2 is the starting point for the entire boot process - well, hopefully it's obvious as to why this is an issue. Why not embed the firmware on the motherboard? Well, being able to update it is a nice thing. Not having to worry about running out of storage in firmware memory embedded on a motherboard years before is also a good thing too; especially when the trade off is a pretty darn minor hassle - IF you ever upgrade your drive (which the vast majority of people never do). If you think this is outrageous, then you must be pretty ignorant of more than a few really gross problems with Intel's TPM (analog to Apple's T2) - many of which can't be fixed without new hardware. At least with this approach issues can be addressed and aren't burned into silicon. Intel could have made parts of their firmware updatable but they punted since it's pretty hard to maintain a secure chain; especially if you are relying just on resources in the computer you are also mucking around with at a pretty low level to update pretty sensitive things. I'd much rather be able to keep my machine secure even if it requires occasional simultaneous access to a 2nd Mac vs. being stuck forevermore with issues in hardware. And even if you use Linux, those TPM bits are still exposed :p Ultimately, claiming access to a second Mac for a Mac Pro (!) owner is any kind of hardship is utterly ridiculous. Every single Mac Pro owner I know (and I have and still use a cheesegrater Mac Pro) also has a Mac laptop since, you know, Mac Pro's are far from portable. And even if I didn't, as a Mac user I have many Mac friends I could bum a laptop off of for the 10 minutes it would take to swap an SSD and install.