this card lacks ROP's

48 isn't much of an upgrade from 32 :/ it's only like 33% more pixel fill sure about 65% more.

should be up near 64 ROP's, though that's a bit much I would went with a re design of shaders that's what the 4,000 series was from the 3,000.

sure they great at what they do but the where taking up a lot of space, the design made them smaller and pack more in there.
( yes I know it's really 160 shaders for the 4870 and 320 for the 5870)