You're comparing a 15.4" mobile workstation with a 2.3GHz or 2.6GHz Ivy Bridge Core i7, 16GB of RAM, and a GT650...to a 13.3" notebook with an Intel IGP, a ULV Core i5, and a max of 8GB of RAM. They don't even come close to filling the same role. If you want to compare the MBP 15" to the Series 9 15", you're looking at a ULV Core i5 at 1.7GHz in the Series 9, still a maximum of 8GB of RAM, still a crappy Intel IGP, and it's less than a pound lighter (3.63 lb).
If you want to compare apples to apples, the 13" Air is a much more appropriate comparison to the original machine you were referring to. The Air has a faster processor (and an option to upgrade to an i7) and weighs almost exactly the same (2.96 pounds to 2.9--not 2.8 as you said).
Enjoyable response given the fact that you brought up the ridiculous notion that the MBP was the lightest laptop of 'it's size'. Of course you are carefully amending the claims now ("lightest of its size using a 3rd generation core i7 with a nvidia 650M GPU and..."), unsurprisingly, but the original point was one hundred percent wrong.
I never actually said the lightest laptop of its size, I said it was one of the lightest laptops of its size, and I kind of assumed you wouldn't be disingenuous enough to compare underspecced ultralights with workstation machines.
If you want to compare apples to apples, the 13" Air is a much more appropriate comparison to the original machine you were referring to. The Air has a faster processor (and an option to upgrade to an i7) and weighs almost exactly the same (2.96 pounds to 2.9--not 2.8 as you said).
So...you were saying?