Hi, I have one mac running Sierra and another on High Sierra. I keep all my data on three external drives and would like to switch the next batch of drives all to APFS. I upgraded my Macbook 12" to High Sierra when it was introduced but had big slowdowns such as excessive shutdown times and slow read-write speeds. I had to revert to Sierra and the performance went back to normal. My Macbook 2011 runs High Sierra without problems. Downloading iphone photos/videos to the external drives takes forever due to conversion from HEIF to JPG. Does this conversion degrade the images? This is one of the reasons I want to switch to APFS. Have you had any issues with APFS? Thanks.