I've only ever had one XFX card. It was gimped on the memory (can't remember which model, maybe 4870) but they'd cheaped out on the components so it performed about 15% below the reference model. I was really annoyed when I discovered this so NEVER again. If you want a card that offers the cheapest components you can get away with fitting on a graphics card XFX are the best choice!
That is something I've found with XFX they always cheap out somewhere in my experience - usually with the product having a fairly defined lifespan. Funny enough my first experiences of it was with the XFX nVidia GeForce FX 5900XT and 5700 Ultra - it is so long now I can't remember what it was but some component on those cards was failing after just months because they used a cheaper part than other brands.