Here's my feelings on the subject (not that anyone really asked for them

)
I agree with Howard that dedicated buttons on a CP make it look very cluttered. If you want dedicated buttons, putting them somewhere besides the CP (speaker panel, under CP, monitor bezel, etc) is a bit better IMO so that your CP stays neater. I still however don't see the need for many dedicated buttons.
As far as confusing people, here's how I feel about that: While I am building a cab so that everyone can enjoy it, I am the one who has to look at it 99% of the time. If you don't like cluttered CPs, don't make one just for others. Also, in my case (and I'd guess most), you'll have a few regular people playing it, not 5 random people everyday, so it won't be too difficult to show the person once and be done with it. If a person is unable to comprehend "hold this button X while pressing that button X to exit" or the like... well... I don't know I want someone like that to even LOOK at my cab, let alone use it. Children would be a different story perhaps, but let's face it.. they aren't going to be reading an instruction card anyway.
Just my .02