It's a tough call. I think it's safe to say there won't be a major update to MC for ages, probably years. So I think O2 should be a stable and permanent world. We should get it right.
I'm not crazy about the cave/mineshaft thing, but I could live with it. Other than that issue I really like this seed. It has a good variety of features. Regular vanilla random seeds are kinda dull (and the plains & deserts are loaded with those annoying little water pools!)
O2 and 1.9 both went live around the same time so I think we should restart. Starting over won't be that big a pain.
We should have an interesting, fun seed, large biomes, a mesa or three; ya know, the works!