[citation][nom]mister g[/nom]Why would I care how much it weighs when for me a die shrink means better performance, or is this G80-G92 all over again?[/citation]
In this case, it's more related to cost reduction. The chip could be actually more powerful (sometimes more powerful chips are cheaper to make), but it will more than likely run in practice close to the speed of the original model. Lower power requirements means less powerful of a PSU needed meaning Sony saves more cash. If it weighs less, it may mean that it would be cheaper to ship.
Maybe a possible price drop to $249-279?