Good idea. Especially since few games can put pressure on even nVidia 500 sereis and AMD 6000 series nowdays (perhaps not maxed and fullhd but still).
I think im better of waiting till the investment has a reason behind it.
Considering that the 290 is a different design than the 280, you can't draw any conclusions about what the 290 can or can't do. The 280X is just a refresh of the 7970 card, and the 290 will have a new design, and the benchmarks of that chip have yet to be released.
The balance of 290X is very different from 280X (and 7970) In some tasks it will be much faster in some other, it will be guite near the older sibling. So you are right, it is not easy to draw conclusion about 290X based on 7970.
What upsets me is with the launch price of $650 or $599 the push for highend cards like the Titan or the fully unleased & unlocked Nvidia K6000 "currently no Geforce version" that has 2880 cuda cores will not release for the market nor prices of current hardware will not lower.
Take back the Maxwell comments the refresh refresh refresh may release first. We all know the K6000 will release but for what price? This is really reminding me of the 8800Ultra vs 8800GTX days.. gr...