[ffcmike]

In theory (I'm not sure enough about the technical aspects to know how much difference it makes) peer-to-peer UDP could be a bad thing if it's around a huge number of players. This is due to the fact that you would be sending data to each and every different player, whereas the more conventional protocol only involves uploading data to the server.
I have had experiences on PC Graal where sparring someone without a great connection but using UDP is silky smooth while there's only a couple players in the level, but then it goes back to being bad when there's a lot more players in the level.

I recall Stefan making a post in a particular thread about the removal of UDP in V6 that he could implement the UDP protocol, but in a way which is still only sending data to the server and not each player. This wouldn't be quite as good as what we're used to among those who use UDP on PC Graal, but it would be a partial improvement for every player. Maybe it's already implemented on iPhone?