So there, pretty soon you'll need a PhD just for picking the right card
Why do you think is radeon oss so much better? I highly doubt that because nouveau is reverse engineered which means the driver does more or less the same as the binary one. Reclocking is however an issue but radeon does not shine in that area as well. Radeon cards tend to use a higher default clock which results in very hot laptops running on oss drivers. As radeon devs do not try to clone fglrx i doubt that the final performance will be that high. From a performance/price comparision most likely amd would win on windows - you pay usually an extra nvidia "tax" of about 10-15% over amd. It depends if you want to live with the linux drawbacks or not - at least 12.11 beta driver is a step in the right direction.
Ok if you take into account if driveres are open source or not that might be a different thing. But I would not spend 400 USD on a graphics card without using the best possible driver no matter if they are blobs or not. I want performance for my money.
how did the power consumption measurements go?
those of us with nvidia chips in our laptops would like to know whether the performance has a penalty