The thing about the schematics showing 756 megs instead of 1 gig of RAM could be the result of the Sensation having being built first. I'm sure they copied a lot of the schematics for the E3D and neglected to change that part in the schematics, but hopefully remembered to change the parts in the BOM.
If not, it'll be interesting to see how HTC will fix it.
Except the Sensation doesn't have 4GB eMMC.
It's either a typo, or there's 256 MB squirreled away inside the 8660, or after 3 months of saying otherwise, they'll change the spec. (Last one - I doubt.)