Yes the R9 290 performs better than the R9 280X.
However, even it is tempting, I'm waiting for the R9 300 series or if i can't wait a GTX 970. GCN 1.1 in on the R9 290 and it is missing some features that even the R9 285 has. GCN 1.0 and 1.1 is pretty old.