I thought it was all but confirmed that because of the low power draw of the system that 600 GFLOPs was a bit too much, if it's even 480 i will be happy, exactly twice as much as the 360's but of course you are correct that there is so much more to a GPU's power than just it's FLOP count.
The GPU's power rumour in the WUST's started off at ~1TF and slowly came down to BG 'calculating' around 600 GFLOPs would be possible but a lot of people doubted whether the system could push to that because of the power draw, who knows, if turns out as high as 600 then i will be over the moon.
Was just giving the guy a short, quick answer as no one seemed to have answered him

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I understand Nintendo cannot compete with Sony and MS in a tech arms race anymore but i still think they should have pushed WiiU to a 1TF GPU and 2GB's of Ram for games. It would have made it so much easier to convince third party developers to port next gen games over if the rumoured PS4 specs of a 1.8TF GPU and 4GB's of Ram are correct.
1GB of Ram and a 600 FGFLOP GPU is going to be hard enough to 'sell' to third parties never mind ~ 400 GFLOPs...

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Of course none of this is confirmed and is just going off past 'speculations'.