For 247, they key could be a little smaller in proportion to the banner. Also, can you orient the key vertical with a solid bar at the top of the banner? Just an idea, fill in the area surrounding the key but below the bar with the background color? Keep the key black.
If you can, submit 4-5 more different shields with the above in mind (see attached pic). Use 2-3 with a rounded top and 2 with a concave top
Also, I would like to see 2 more non shield (again see attached pic)