Currently plone-patterns-toolbar is loaded for anonymous, in https://github.com/plone/Products.CMFPlone/blob/master/Products/CMFPlone/static/plone.less#L8, instead of in https://github.com/plone/Products.CMFPlone/blob/master/Products/CMFPlone/static/plone-logged-in.less
May we move that in order to get a slimmer site for anonymous? I also think it's more intuitive to find it there.
+1 - targeting Plone 5.1 only.
How much compressed javascript transmission does this save?
Well, toolbar.js is 14.5kb and toolbar.plone.less + variables.less is 19.5kb, making for around 34kb but that's before compiling/minifying/gziping. There's probably also some blocking in browser's time to interact, both for parsing and rendering.
Definitely. It should be in the logged in bundle.