Yeah I should have clarified: All gaming laptops need a cooling stand + plugged in for full performance.
The battery comment was more for non-gaming / lite-gaming -> battery life wouldn't be as great there as a single GPU.
(I'm not sure how good the powersaving options are, whether you can 'turn off' the physical GPUs. And many applications use GPU acceleration)
Tbh I'd only really go haswell if you plan on using the IGP (integrated graphics), not enough of an improvement to justify the hefty increase in price. (Slightly cheaper desktop wise, but still a mark up e.g. Motherboard + CPU)
Agree on the last part, MSI laptops tend to be very hard on the eyes + pretty cheaply built.
It would be worth looking up reviews.
But you do get decent hardware at a lower price and MSI has a pretty good warranty + RMA service.
(I would check out the warranties on all the laptops, don't want to get shafted with some minimal excuse for warranty).
Lenovo is a higher tier brand, you pay the extra for the guaranteed quality build + looks.