Are they split in some way? I just think that past 14 CUs the CPU or something else in the system is starting to be a bottleneck and you get overall better performance/balance by dedicating a few CUs to help/boost the CPU.
I think we reeeeally need official specs. I get the feeling that people here and at GAF have been speculating for the past few weeks over a mixture of pure speculation and misinterpreted info.