After having made a few panels with several different layouts, my only comment about that layout is not the number of buttons, but the placement of buttons 7 and 8 closest to the joystick and offset a little bit.
I would only guess that those buttons might get in the way when playing 4 or 6-button games (fighters) and having to find a place to rest your thumb.
For console games, you really need all of the buttons...at least 10 (unless you go 12 to account for L3 and R3 in PSX games). I used to think the world revolved around Capcom and I only needed the 6 buttons, plus the START...then Sammy came into my life. To play Guilty Gear XX properly, you need all four shoulder buttons. Two for the HP and HK, and the other two for selecting the EX and alternate costumes.
Hope this helps.
Bottom line: Stick with the number of buttons and find a different location for the two closest to the joystick and offset. That is your thumb's resting place.
Chuck