Follow up: It works, but it's not perfect. For example, when hovering the mouse over the titlebuttons you get the same color scheme as default Plata (ie. big red circle over the close button), and it didn't quite take all the way on Firefox lol:
Plata w/ Vimix Titlebuttons
Plata w/ Vimix Titlebuttons on Firefox (after a system restart):
Edit: Firefox uses the 'window-restore' tittlebutton for 'maximize' - works now, but very messy: