I don't think the big controller is
that bad. It's probably because I'm used to it though. I love the small one, but I get ruined in Halo when I use it.
And yes... get a new one. If the drive gets fucked - like Chojin mentioned - it's not going to be under warranty.
Edit: At least that's how it is here (Ontario) at EB. My friend purchased one of the older models that was prone to fucking, and after 3 months MS wouldn't service it for free. :/
Edit 2: I like my edits in italics.