Challenged to find space in my backpack and limited to just one bag by the airlines, my friend suggested we vacuum seal my gis. I didn't think an A2 was going to fix in the 11" wide roll-style bags but it did. We removed the air and when we were done my gi had shrunk down to roughly the size of a five subject notebook.
Its not the perfect choice for all trips. You'd need to re-vacuum seal and without the machine your stuff would never fit going back. But for the right situation, say taking a bunch of gis on a one way trip it'd be a great space saver.