Just a heads up that Mac OS Sierra has some major issues:
- windows redrawing slowly and funny glitches on my screen. (still not fixed)
- time machine backup is broken – I cannot backup or restore from time machine back up. (still no fix. Apple have some suggestions about resetting the PRAM but that didn’t seem to change anything.)
- downloads not working in Safari – they stop before the download has completed. (now fixed – Dec 2016)
So if you are thinking of upgrading to Mac OS Sierra, I would be holding off until at least the first software update.