Interesting project More and more financial institutions are starting to implement messaging using the FIX protocol http://www.fixtradingcommunity.org/pg/main/what-is-fix
Its' no longer suitable for market data. Its barley suitable for sending order messages around. And with the explosion of order types and growth I'm not sure that's a valid statement anymore.
Its not anywhere near as compressible as binary formats. Many exchanges and dark pools have already replaced it with binary formats.
What fix does have going for it are quickfix/j and a wealth of knowledge, which will keep it relevant for a long time, but