I am the proud (former) owner of the XFX R9 280X Black Edition Double-Dissipation GPU. It was a great card on all accounts, and I have no problems recommending the brand to others.
One thing that is often overlooked with the Black Edition units is that they are specially binned so that they are factory-overclocked while using the stock voltage.
XFX has put a lot of time and effort into perfecting their cooling solution over the years; they are often the top bracket of performance, although using only two fans instead of three can hurt their acoustics some. With the higher-end 300-series, they've updated their cooling solution (Ghost Thermal 3.0 now, I think??) and I look forward to seeing to what that brings to the table.