Good recollection on mario.. the first time I played SMB was in an arcade..
My comments about Sonic arcade have to do with capturing the feel and the energy of the originals.
not sure if it is entirely relevant but genesis was after all a scaled down arcade board..
Arcades experiences are more intense and more of a rush and I think that fits original Sonic better than he has been done today... though I realize a Sonic arcade game is not a practical or realistic proposition. maybe if you could do the arcade games episodic, as well, and find an easy way to add the extra levels..
joint arcade and home leaderboards.. there might be an idea there, vaguely..