I wouldn't. I would wait for the next round of cards to be released(should be soon?). It wouldn't be a large enough upgrade to justify the cost with the new cards being right around the corner, in my opinion.
For sale I have a XFX 290x, it is water cooled with a black acetel/nickel EK water block and a black back plate. It's been under water from day one for silence. I bought it new from newegg and never used for mining.
$290 obo shipped
Water Block -...