They went all the way adding GTX980 and forgot to include PCIe SSD instead of mSATA ... some times you never understand why ...
The combination of dual heatsinks/fans, removeable DVD or Blu-ray Drive, HDD, and battery does not leave enough room for the longer high capacity M.2 SSDs, this picture will show you why
http://i59.tinypic.com/2eary84.jpg Those mSATA drives are just short enough to fit, if they were M.2 drives you might get 256GB drives in their at max while the mSATA lets you get 1TB drives (I've got a Samsung Evo 1TB mSATA in my P25W v2 from earlier this year).
If they had made it any deeper or wider this thing would have become a 17" laptop the size of the GS70, that or they go the GS60 route and ditch the ODD.