With a Legacy head, I'm not sure about the 2. But I'm willing to bet that the Greenbacks sound great. My friend almost dumped his Diezel head for a VHT until he plugged it into an OLD Marshall cab with the original Greenbacks. His head never sounded better. There is no "right
speaker cab". Just what sounds best with your head and playing style I suppose. People talk about speakers "breaking up" at certain levels. But I don't think most of us would play consistently at a breaking up level to worry about it. Personally, I don't like any speaker that sounds brittle or thin at any level. Warm and punchy is good. I use a 2x12 Legacy cab. It don't punch and wonk like the 4x14. But it's tighter than a combo. And lighter than a 4x12. I often wish I had a 4x12 for cranking when the wife and kids aren't home so I can rattle the windows. But again, the 2x12 is plenty really.
Yeah, that' wasn't much help. But it's all I got at the moment. I think I heard the v30's are a bit more midrangey.