@BadMouth, due to the inclusion of the XBOX layout in a smaller font in buttons 2,3,6,7. If I use letters, there would be an A where currently button 1 is, but there is another A label in button 6 for the XBOX layout, this would be the same for letter B,X,Z. As mentioned in my first post, this letters was the original idea, but changed to numbers because of this.
@lacanian, yes I looked at layouts from madcatz, hori, eigharc (qanba), some start with buttons the xbox layout (would be the same idea for the Playstation layout) "A B RT LT" , and others with "A B RT", I went for the former as it seems that it would make more sense leaving the left shoulder buttons on the left, and same for the right, otherwise you'll end up with the left buttons on the far right.
@RandyT, what do you mean by just mirror the buttons to both rows? I see this working for games with 3 or less games, but not sure how it would work for street fighter, etc.