If i had bought an rx-8, and they sent me a letter saying they'd buy it back for full price, i'd probably romp around in the car for half a thousand miles doing drifts and god knows what else. THEN ask for my money back.
But in all seriously, that's big of mazda for doing something like this. As some already said, nobody will notice the measly horsepower difference. It's just the right thing to do to admit that they didn't live up to what they advertised. Plus, they're smart for confessing before the press chewed them out and inadvertently destroyed the rx8 during it's first year.