I can confirm the PS3 is G2!!
Check this out at 1:23 you can clearly see the disk is central in the case with around 3cms gap at top an bottom:
http://www.youtube.com/watch?v=SMeiEyOj6n0
Now check here - ok the quality is pants - but at around 6:07 you can see the disk is nearer the bottom (around 1cm) and there's about the same amount of gap at the top of the 360 version:
http://www.youtube.com/watch?v=eqZ-f-ovRA8
Happy days!