Even if you have to plug it in, a laptop is still far more portable than a desktop. If you're moving about and working in different areas, but still have access to power then a laptop could still be a better solution.
An iMac is portable, a Macbook is mobile. I'm hoping this is mobile, but knowing the PC laptop world my guess is <2hours of battery under serious use.
My question is will this need to be tethered to a power outlet to use? Is the battery just so your machine doesn't shut off while moving from room to room?
Personally MacBooks have a good battery but I'm _still_ debating buying an external battery to keep that running longer. I wonder if you could modify the HyperShop batteries to work with PC laptops...
They're claiming 6hrs of "productivity" and 2-3 hours of gaming, which is about what I get with a less powerful 13" retina MacBook Pro. Granted, this is also 1000 dollars more expensive.
from your post I would guess that you have not experienced the joy of intel haswell based laptops my laptop lasts 7 hours or more on a charge when in power-saver mode. There is nothing special about it besides the fact that it is current.
You are going to have alot of fun the next time you get a new machine!