If you'll like the more aggressive position that those bikes give, then either is a fine bike. I'd probably go for the SuperSix. While I like my current bike with Di2 the Ultegra 6800 group is nothing to thumb your nose at. I suspect the SuperSix will be lighter and that will make more hills seem to disappear. And if that is the one that comes with carbon wheels then that will give you a superior feel for the bikes handling on the road.