It will be nice if the development team could centralise all the custom coding in one place. I mean the 'Head Section' and the 'arbitrary HTML' should be taken away from the page properties section and added to the Arbitrary HTML. It will be nice to have a CSS Section too. Maybe the word arbitrary HTML could be change to custom code. This will improve efficiency and help non-coders to know what goes where.
Another issue is with selecting the arbitrary HTML when you have lots of other items on top of each other, it becomes tedious and strainous finding the custom code you want to edit. A possible solution is for Muse to enable the designer specify a folder where external assets are placed and Muse can detect and display accordingly in the design view(Preferences/settings). This would improve designers work flow since they are led more by what they see , they won't have to export to HTML and preview in the browser before they can visualise their design. It doesn't work that way in Indesign/Illustrator/Photoshop, why must it be like that in Muse?
Another issue is the need to always 'right click' to take advantage of a tool options. Can't we have a system where when you select a tool or make a selection, the Muse changes the set of options available on the bar like indesign, photoshop, illustrator.