that is just because they have different chipsets
My broken intensifi card (same chipset as in the router) wich had a max speed of 135, actually did get a 135, and received the max 270.
dunno how fast the intel card receives, but it should be also around the 130 or bigger.
asus says they will upgrade to the lastest N technology if it doesnt work, even if they have to replace the chips, but... they just don't, because it works a bit