The only claim I've seen about being superior to full frame is specifically related to resolution. As a camera being compared to the 5D MkII I'd say the differences in operation, lens choices, and ergonomics will be a much bigger practical difference than sensor performance. To me the statement from Fuji (on sensor performance) is more about taking their camera seriously than saying it is a good alternative to a 5D MkII. They are very different systems - designed for different things.
I don't think this system is targeted at your typical microstock shooter

Very interesting, though !