It' safe, I did and didn't have any problems, everything was fine and smooth with me. Give a try. BTW on ionic 2 docs they say it's safe to do that.
http://ionicframework.com/docs/v2/getting-started/installation/
Worried about your V1 Ionic projects? Don’t worry! The alpha release has all the functionality to work with both V1 projects and V2 projects.