Unfortunately power doesn't come along well with portability and price...
Either its a powerful and heavy and not-too-expensive laptop; or a lighter but less powerful and not-too-expensive laptop for you 

My opinion on the Y580? Its the best budget gaming laptop at the moment
At least until the Y500 with an additional ultrabay GPU is out and benchmarked

The new Y400 and Y500 series laptops are basically normal laptops, apart from being good-looking, they feature something called an "ultrabay" (a tray-like thingy that lets you put in an optical drive/ heat sink/ additional GPU   etc.) These bays are usually only available in business-class notebooks before this.
Although the new Y500 series were speculated not to come with a GTX level GPU like the Y580 does. The combined performance of 2 GPUs will most probably be better than the Y580. But still, its too early to tell 

Its a good all rounder laptop, its not the best by a big margin
Hmm, I don't think that's the case, the correct phrase should be "W8 doesn't work that optimally without touchscreens" But that's only for the tile menus... the desktop and everything else seemed to be similar to W7