I agree. I think the devkits right now are using GDDR5, but if they can move to Wide IO it'll be for the best.
None of this is final. Final devkits will ship in the Summer. Do not look at this and expect everything to look 100% the same. Things can change either in a positive or a negative direction. Do not expect any major revisions (switching from a 8850 to a 8970), but expect things such as clock speeds to be tweaked until release. This is a giant balancing act.
Some good information has come down the grapevine that the VGleaks article was almost 100% correct and that Sony has upped RAM to 4 GB. It is 192 GB/S unified

. Also the Durango specs have been leaked and apparently some mystery sauce is at work.
Through PM I was just told I am almost right. This is your Orbis folks
.