I have it. And no I don't regret it.
But let me explain why I chose it. First off there are 3 Sapphire 280x models. The Dual-X is the low end one. Also the 7970 was, and is, an excellent GPU; so simply changing the label to a 280x isn't much of a change and I gladly paid $315 for a 7970. A Toxic one would be great but kind of overkill in my opinion($50 more), so I wanted one that ran cool and quiet and so far my Dual-X has done so @1100MHz.
What helped me decide was the price and the 7970 Dual-X reviews. And I wanted a mild overclock since at stock the 7970 can max out BF4. What more do you need?