Yea, dont take these specs as absolutes, they are speculated specs if you will.
As far as slightly smaller vs behemoth chips, xbits has an excellent review showing the 4890 in CF holding its own vs the 285 in SLI.
Lets face it. nVidia has turned towards the gpgpu solution, and thats a major part of their strategy as well as their die size. Theyll be going DP in a major way for this, and that costs realestate on the gpu. Theyre trying to drive the market in this direction, trying to preempt LRB, and want to compete and lead in that market. What I wonder is, will they continue heading in this direction , having both gpgpu and gaming perf together, or make 2 units, each aimed specifacately to each market?