Anybody played with this yet? I'm wondering... - Can older iOS versions view images in iCloud Photo Library that were taken by iOS 11 phones? - Can Sierra open these things? - Is there a way to set the quality? If you can get the same quality at a smaller file size, I'd much rather get more quality at the SAME file size as before. Disk space is cheap. I'm mostly concerned about how compatibility issues will be resolved between iOS and macOS versions that support/don't support HEIF. I'm glad they're making it optional.