After extensively searching on Google I think I finally pinned down to problems regarding the commands:
ionic serve
ionic emulate <platform> // or anything else cordova related
which lead to node.js errors on the cmd line on Windows, but work perfectly fine on Unix OSes. Those ionic commands make use of the childprocess routine “watch” of node.js, which fails on Windows if the cmd line arguments are not provided correctly. “Ionic serve” invokes the “gulp sass watch” command, now failing for any new project with SASS support on windows.
I’d love to help out here, but my .js abilities are far too inferior to be more useful than that.