Well there been some intresting points made that when the 5870 is underclocked to the same speed as the 5850 they perform the same.
This looks like that on the surface that the extra streams and texture units are doing little for the 5870 in most games and that it's the back end ROPs that are more important (the 5850 and 5870 have the same 32 ROPs)
So how is the 5830 going to be for ROPs? and will the reduction in streams&texture units actually come into play?
Still if the estimated price is correct around £185