I personally think the cheek indents need to be there unless you are doing a legacy helmet. In all of the available pics in movies and comics they modern mando bucket has the cheek indents. The real issue is that it begind to look like a midevial knight or something from Ren Fair instead of the Star Wars universe that it is supposed to originate from. The remainder of the idea looks workable. I would alsoprobably run the T visor all the way to the bottom, again for the same reason listed above, but this would detract less than the lack of cheeks.
just my 2cents