If you can get a Rod of this, that would be the best use of the feat. That way, on the occasion that you're able to set up an ambush, you can whip out the rod and create a completely inhospitable battlefield for your opponents. Classes that are able to add Metamagic for free and on-the-fly like Ultimate Magi or an Incantatrix could also make good use for it if, somehow, they had a spare Metamagic feat lying around.
That said, I don't see much room for cheese. It's really only going to be persistable (in a practical sense) by using one of those classes that gets plain obscene metamagic abilities already (like Incantatrix).