Credentials: built controller last summer and played with it a lot for a month before I left it to go to school (thought it would be distracting).
My layout was like yours, except the 6 were straight aligned. The 7th was down and to the left (but too far away IMO- yours looks good, though I don't know about the tilted 6 as I've never actually used them; it does make sense from a look-at-the-different-lengths-of-my-fingers point of view).
It'll be fine. Map the '7th' button to 1, so 1234, and 567 above. Then the majority of games will use the bottom ones that are easy to reach and you won't even notice the others. If you want to play a game with the SF layout, just rebind the keys (it's no big deal unless you think you'll be playing a couple of different NEW fighting games EVERY DAY! the binds save:).
I really liked the 4-in-an-arc layout for NeoGeo, and the SF 6. As long as you start 1 from the buttom left, I can't see how the others will bother you. So it should be great!
Good luck.