I will say this once then im out,
the only reason I think a save button could be helpful is because of this:
when one saves work, its a huge deal, we want a visual to know our work is saved, we want to see this button being pushed/highlighted as we press it.
I happen to use control +S to save all the time except for when I exit sonar or need a visual on a save, that's when I use the toolbar, because I want to see that button being pressed.
I want to know for sure I have seen it pressed.
so for the amount of time I use it like this, I see no reason for it.
but then again. im only an opinion.