I've been thinking of installing the Sierra DP on my external SSD. This will give me a chance to try it out, and use El Capitan as the main OS. However, I've been wondering, will logging into my Apple ID/iCloud Account somehow mess up the data for previous versions? El Capitan made the Notes unusable on older OSes, for example. I'm guessing there will be no problems, but thought I'd ask here anyway.