Agreed, it would have been tricky to be 12.5% one color attribute and then convey to the player what that breakdown was. Then how do you handle merging that later? The same level requirement makes it a more clear 50/50. Given more time, I'm sure you could implement highlighting other possible merges when you are dragging a tower, or a mouse-over tool-tip to make it a little easier to compare the level of different tower types.