Icetea compression

What are the advantages to compressing in icetea when creating an eboot from a psx iso?

Lower file size lol. :)

Honestly, the only reason you WOULDN'T compress is if when you DO compress it mucks up the game somehow.

I don't know the logistics behind it, but it drastically reduces the file size with (usually) no side effects.
If your game doesn't play correctly then I would set the compression to a less drastic level.
But usually you won't have any problems.