Dunno about this Groves bloke really. On the one hand, he caught an under prepared Froch on the hop last time, and still couldn't put him away, so his chance has probably gone. On the other hand, he has clearly got under Froch's skin in a big way.
As for Froch, you can either see him as a an unconventional fighter with bags of natural ability, or you could say his technique's all over the place; Groves has clearly been studying him, and has identified his weaknesses.
As for who's the most resilient, Froch has proved himself a true warrior with the ability to take a punch, but that catches up with you in the end. His granite jaw is a strength that could turn out to be a weakness. He had Groves at his mercy when the ref _ in my opinion rightly - stopped the fight the last time, but Groves is an improving fighter who is younger and fitter.
I suspect Froch may just have too much ringcraft and too much power for the younger man. But he'll have to be on top of his game, because Groves is a man with a plan, and the relative lack of experience will be compensated by legs and arms that are 10 years younger.