So for the last year, I have been booting my iMac from an external 256GB SSD plugged in by USB 3.0. I'm changing my desk setup around and am not going to have one my externals plugged in all the time anymore. It was the one I was using for Time Machine. I'm in the process of backing up my SSD now, to my internal iMac hard drive, which never gets any use. It literally had 900 GB out of 1TB free. I got the machine and immediately started booting to SSD. Do you see any issues with this? External SSD boot backed up to the internal drive?