While I consider your ideas in general to be a little off the wall but fantastic, I really would like to see the sun and moon stay square. As a fellow game dev I'm sure you understand the importance on internal consistency and changing the sun/moon to pixely circles makes things feel more pixely and less minecrafty.
Now I will say that the round ones do look nice and are well made, I just think that the square ones reenforce the the world image you've worked so hard to make.

-John