I was in this position before I bought my XFX 5850.
Argument for a 470:
eVGA support is awesome. They're a first rate company and they will treat you right. I've had to replace 2 GPU's with them, both times I was returned a card of higher caliber. (6600GT -> 6600GT OC, 7800GT -> 7950GT). Down time was minimal in both cases and my shipping was covered both ways. The simple fact that reps on the eVGA forums promote OC'ing and tweaking that most companies dance delicately around was really nice as well. I would go as far to say that EVGA gained my business when they backed up their products. A lot of companies claim products that are designed to OC well or are highly customizable, but when it comes to getting help doing that, you get silence in return or warnings about your warranty.
Argument to Pick up a 5850:
XFX also has a lifetime warranty, and IMO if you go with a reference cooler model (didnt see you mention OC'ing it) I don't think you'll run into problems as most of the complaints I've seen are with non-reference designs.
The 5850 was also a no-brainer for me in terms of heat, efficiency, and bang for the buck. This is my first ATI card in almost a decade and I don't regret it one bit. I sure don't miss PhysX either.
In the end, I think I miss having an eVGA card more than having one made by team green.
Also if you think about it, there's always something slightly better for a little more cash. If you get caught in that vicious cycle, you'll be justifying purchasing a 5970 in no time, lol. Buy what you need for what you want and for features that are important to you. For me, this was a 5850 due to heat, power consumption, and performance per dollar.