Hi,
I'm a owner of the Razer Blade Pro and my bother is a owner of the GS70. We've both swapped the units to use and compare to see what is the key difference between the two laptops. Both belongs to a same class of laptop but both are actually very different machine. According to what you want to know, i will give you the thoughts and opinion of both me and my bother.
Spec: GS70 wins. The hard drives space itself wins it for GS70. But if you don't mind carrying an external hard drive with you, i guess it's a tie between the blade pro and the gs70.
Portability: Honestly, its a tie. The GS70 is a hair lighter if you put it on the scales but in real world usage, i don't notice that hair difference.
Gaming: IMO and my brother's opinion, we have to give it to Razer Blade pro. The keyboard is the key point. While the GS70 has the SteelSeries keyboard, it doesn't feels as solid as the Razer Blade Pro's keyboard.The Blade Pro has a additional reinforcement behind the keyboard which gives it zero flex and it just felt slightly better.
Editing/Work: Once again, we both felt the Razer Blade Pro takes the win. What makes it the winner for us is the Switchblade UI. With special apps dedicated to Maya, Photoshop and other program, it really helps out with work.
Noise: There could be minor differences but in real world usage, we honestly don't feel the difference is big enough to notice. So tie.
Heat: Razer Blade Pro wins. GS70 simply just have a poorer cooling design. It's proven and benchmarks have been made to document this.
Overall: There is no clear winner here. Depending on what you want and what is more important to you, either laptop is a winner. For me is the Razer Blade pro. The reasons are:
1.) I really love that keyboard. How a keyboard feels is really important to me. When i type on the Blade Pro, there is zero flex at all. I'm also not a big fan of multi colored lights so i don't really care if the steelseries keyboard can let me customize the lights to a gazillion colors.
2.) I felt the razer blade pro looks and feels more professional. I wouldn't feel awkward to pull it out in a meeting or appointment with a client. Not to mention, it just feels better build. It's body is 99.9% metal unlike the GS70. An area i would like to point out the the screen lid portion of the chassis. GS70's lid flexes much more than the blade pro. This is also a fact that is documented.
3.) The battery life is slightly longer.
4.) I actually make use of the Switchblade UI for work and for system monitoring. So that is a real plus for me.
Now my brother feels the GS70 is his choice. The reasons are:
1.) He really appreciate the extra storage space on the GS70.
2.) It has more ports. He has a gazillion peripherals and device he hooks up to this laptop.
3.) It's more user upgrade friendly. He like to tinker around with hardware.
4.) It fits more into his budget.
Having said all that, comparing specs on paper is really not a good idea unless you are that kinda person. We buy the laptop to use. So what is important to me is which would feel better to you in real world usage. Which you would feel better using and feel good about. No doubt the Blade Pro is much more expensive than the GS70 but i am willing to fork out that difference because i felt i would feel happier and enjoy using it more that the GS70. Is it a justifiable $$$ difference? To ME, it is. I'd rather pay more for something that i would enjoy using or owning than laying out money just because it's a more "logical" choice. My brother is the entire opposite of me. He feels GS70 is more "logical" choice so he got that. All in all, both laptops are winners in our eyes. Go to a shop and feel the laptops for yourself and then make your decision. Good luck to you!