The Playstation wheel buttons may look a bit silly, but having lots of buttons is very helpful. I only see six on the momo, the PS button layout gives you way more buttons, and I use them all - the directional buttons for looking around, the l1 / l2 / r1 / r2 buttons for F9 thru F12, start for the horn, and I have things like the pit lane limiter and the handbrake mapped to the cross / square / circle / triangle buttons. I'd be a bit pushed with only six buttons on my wheel...
if momo has more buttons I can't see then this is negated, of course.