<div id="linkdxomark">This a comment for <a href="http://www.dxomark.com/index.php/Cameras/Camera-Sensor-Database/Canon/PowerShot-G1X">this page on the website</a></div>"You have a reflex-quality sensor in camera of the same volume as a G11."
No you don't, the GX1 is much bigger than the G-series.
Define 'much bigger'
In these pictures from DPReview, they seem to be very close in size.
From the top view, The G1X even manages to have a thinner body than the G12, except for its slightly potruding lens.
This is amazing don't you think?