As for 802.11y. Its seems like a good choice until it comes to implementation which is very very new and what IC's? Programing it will be new?
And as Ash pointed, we will compile pros/cons soon, moreover, we shoild also get info on what modules are available in the market which impliment WLAN and compare them too.
Till then here is the wiki on 802.11a/b/g/n/y :
IEEE 802.11 - Wikipedia, the free encyclopedia
EDIT:
I tried looking for some info on this, but mainly the wiki gives info on ranges. Power consumption may vary a bit between different vendors and implementation IC's.