I would not choose a gaming laptop for both reasons already mentioned:
1. Gaming systems usually employ a TN+Film panel for fastest response time, but colors shift significantly with viewing angle. Even viewing straight on and not moving your head, the screen is large enough that the colors will shift from one part of the screen to the other. When it comes to photo editing, I would say IPS is your best bet.
2. With a gaming system, a lot of the cost is in the graphics chip, and that is largely wasted for photo editing. Better to put that money into more RAM (Lightroom can never have too much!) and a solid state hard drive for your system drive. A second drive bay could be used for a high-capacity traditional hard drive.
I'm going to pick up a Dell Precision M3800 mobile workstation shortly. It has a 1920x1080 Ultrasharp display (IPS), 8GB of RAM and a decent processor. I'll probably add another 8GB of RAM for a total of 16GB (cheaper for me to do it than Dell). There's also an optional 3200x1800 IGZO Ultrasharp display (IPS), but you then have to "configure" your laptop, which adds another $60, then the screen upgrade is like $79, so to have the high-res display adds about $139 (and I'd rather add RAM). Most of my editing is done on an external monitor, but it's nice to have an Ultrasharp on the lappy.
One downside is that because it's a touch display, it's glossy. Not a fan of glossy displays. Other than that, for price, performance and size (.71" thick, 4.15lbs), it beats anything else I've looked at -- even the HP Z-Books.