[ffcmike]

The problem with solely using MP3s or OGG for me is simply their sheer filesize having to download, for the less fortunate this can take a while but even for most people there'd likely be a delay the first time it is played.

The way I have it setup on Classic is to play Midis by default but there's an option for players to enable MP3s (if not turn music off altogether), though there are only a select few converted mainly where they have been used as part of content or playback varies more highly as opposed to all of them, I also use a scripted preloader that downloads them beforehand within a level or 2 before the first location you can expect them to be played when the option is enabled.