I'm leaning towards CGI. I think the new Ninja Turtles movie will be the acid test for this idea of running these characters for a whole film. If it works and is affordable, it could be awesome for the FF. Having 18 minutes of thing ala Avengers isn't a plan though, that won't cut it.
The Ultimate Uniforms are really solid. The only thing I would say is focus on the later dark blue and light blue thing rather than the black and light blue. I think that the former mix makes the team a little more super. Also, giving Thing a top sets him apart from other CGI musclebound freaks, and even the previous shirtless Chiklis Thing. A smart move all around.
But at some point, I want to see the Future Foundation Uniforms. They'd be so glorious in some future film.