Nope, 470MHz is completely stable, and on stock air.
Actually, a lot of people who do have the same card managed to get much higher overclocks than me. Some have gotten it to 500MHz with Air, although I'm sure that's rare.
Either way, going from an X800, not that it's a bad card to begin with, you may not even care about overclocking it further, unless you are an overclocking junky like me.
There will be a world of difference, so any way you go, you will not be kicking your ass later.
Intel Core i7-3960X, GIGABYTE G1.Assassin 2, Kingston 16GB DDR3-2133, NVIDIA GeForce GTX 770 2GB
Kingston HyperX 3K 240GB SSD (OS, Apps), WD VR 1TB (Games), Corsair 1000HX, Corsair H70 Cooler
Corsair 800D, Dell 2408WFP 24", ASUS Xonar Essence STX, Gentoo (KDE 4.11. 3.12 Kernel)
"Take care to get what you like, or you will be forced to like what you get!" - H.P. Baxxter
<Toad772> I don't always drink alcohol, but when I do, I take it too far.