Speaking of West End games, has anyone here played Paranoia? That's is a truly fun and incredibly silly system.
I like D20 for its simplicity. There aren't a lot of complicated exceptions to every situation. However, there are unrealisitic things about it because of the simplicity. For example, when one character is chasing another, its perfectly possible for one character to catch another simply because people take turns running, rather than running at the same time.
As for multiple characters per person, its cool if you don't have the players, but I have always liked it if you can get a one to one ratio. Having multiple characters per person tends to lend itself to party unity quite a bit, and some of the most interesting parts of role-playing are when the characters disagree about something.