The whole point of overclocking is to get a cheap product for which you know may be clocked A LOT more than it is... that goes for pretty much any component, "get" a product that's priced sometimes twice as much by overclocking the cheap one (obviously "get a product" means "get a performance of a product" no need to explain really). People usually miss this value of overclocking and replace it with ... oh I am gonna get that 1fps more even if I had to spend tons of money on cooling... or whatever. Silly.
My Radeon 9800 NP is by default clocked at ~ 300/300 so after flashing it to pro and overclocking it I got a product that runs 430/380 speed which is pretty much your 9800XT level.
And I got that for half the money I would have payed for the XT, and all it took is a little bit of research on released models of 9800 line of products
I bet you that we are not talking 2-5 fps gain here.
Similar story goes for my Barton 2500. It runs at 3200+ performance level for more than half the money.
Call it a steal!