In fact of the matter, Claymore's miner can mine at 22 Mh/s now on 7950/70.
Much earlier I've written analogously post but even Claymore did not notice it.
But it's repeated again and again. And not only for ETH it has higher hashrate for SIA.

It's 6x7950 rig today:
http://i66.tinypic.com/bhg4dh.jpg

Here is log for R9 270 Rig was working at 6x15.7 Mh/s:
http://www.filedropper.com/logrigr9270

I'm asking Claymore to check it.