The problem with the unisinks are that by the time you buy the GPU block and then the matching unisink, you've mostly likely spent as much as just buying a full cover block. I say forget the unisinks and just go for full coverage. Sure the GPU only blocks are going to be more compatable, but then you have to direct a fan at your card to cool off everything else which normally looks kinda weird.

BTW, anyone have pics of what the 5870's heatsink looks like under the shroud? I'm wondering if it is like the 4870 where you can leave the stock plate with fan on to cool the memory and VRMs while a GPU block covers the core.