I would like to question those saying that we have to follow the SNES style (be it with Greek letters, BAYX, 1234 or whatever) because it is some sort of defacto standard.
I think Sega would be more the 'defacto' standard in button layout on controllers today than Nintendo. After all, Sega always had their button placement as ABC (and later ABCXYZ), rather than BAYX. The Dreamcast then cemented todays standard, used on the xbox/360 controllers, with it's ABXY layout, A being on the bottom and B on the right. Even Sony, who use symbols rather than letters, adapted this sort of standard for select and cancel, using X for select and circle for cancel (In US and Europe anyway - I believe that Japan does it the other way around).
It's only Nintendo who have placed the button lettering 'backwards' - in what language does B come before A?
So for those wanting to adopt a button labelling because it is the 'defacto' standard, then it should be Sega and not Nintendo that is followed, since they DO have some sort of defacto standard. And I will of course be playing some both some snes and Megadrive on my Pandora when I get mine (and Saturn - IF it's ever attempted that is).
(Slightly off topic - while reading the threads about buttons the past couple of days, I've realised that when I played snes on my GP2X, I placed the buttons using the Sega method rather than Nintendo's, ie A at the bottom and B on the right, without even thinking about it - that's what I get for being so used to Sega's button layout - and guess what? It has never hampered my enjoyment of snes games one little bit. I'll probably do the same again on the Pandora without even thinking about it too. ).
But really, does it matter? After all, if someone who can't work out to map the buttons to mimic the snes when emulating it and use that, no matter what letters/symbols/numbers/whatever are on the actual buttons must be pretty stupid. And again, if they can't work out when they are playing snes and when they're not and use the buttons accordingly, well, again, they can't have all that much brain power.
EDIT: quartercast - you make a valid point with your button labelling, and it would be very interesting if your suggestion was used. And it wouldn't be a bad thing either. But as I said/wrote in the paragraph above, I'm not too fussed with what's on the buttons in the end.