Another drawback for the Gluttony-villain can be that he [i]has[/i] to eat a lot, so he'll need a lot more nourishment than the usual human for all his bodily functions to work well. I can also imagine his system consuming a hell of a lot of energy to digest all the weird stuff he gobbles down. I also imagine he'd be spending quite a bit of time on the crapper, for what isn't spewed back out of his maw. Yes, this is going to be a character who'll definitely win the heroines' affections. 

In regards to the envy/greed discussion, I found that Greed is a selfish desire for more of something than is needed, where envy is a desire to possess something that someone else has. Greed is about oneself; a selfish wanting to have more, while envy is about what everyone else owns, and a wanting for those things. At least, that's what I found.