I have been using this laptop for 3 month now, here is my mini review:
-Keyboard is very good
-Screen is very good, colors are awesome, you may have to use the setting though as on mine I couldn't see properly dark video or shadows.
-Touchpad is very bad, not the worst I have seen but for that price it's a big let down, my old K 17" asus was better than. It's very bad, it often mess up my navigation tab on chrome, or it zoom randomly at 300%.
-There is coil whine on it, noticeable like it's a HDD but there is no HDD in mine as I put a SSD. Another let down for that price, my old K Asus didn't have coil whine. If you have a HDD you may not notice it though as it's exactly like a HDD noise.
-The laptop is very quiet for a gaming laptop, if it wasn't for the coil whine the silence would be perfect.
-Graphic card does his work, very good.
-Build quality is very good, very sturdy.
-There is enough usb port on either side for a 15", that's good.

Overall it's a very good laptop, if it wasn't for the bad touchpad and the coil whine it would be a perfect laptop for me.

So, you're not going to correct what you said about NVMe drives in your review?

6 hours battery life for gaming notebook is terrific. this is the correct way configuration as a gaming notebook. i choose gaming notebook as my daily basis use notebook. because i need gaming + paperwork . i hate my power adapter.

Weird! This laptop is advertised as 2.2 kg in weight, not nearly 2.5 kg.

Even the exact same model you've used in your review, the "GL502VT-DS74" is being sold on Amazon by EXcaliberPC in a configuration that features a "256GB Samsung 950 PRO NVMe SSD".
https://www.amazon.com/GL502VT-DS74-i7-6700HQ-Windows-Ultraportable-Notebook/dp/B01FSARGXA?ie=UTF8&*Version*=1&*entries*=0
So this laptop definitely supports NVMe SSDs.

Yes there is support NVMe PCIe SSD
You can read here on official page
https://www.asus.com/ROG-Republic-Of-Gamers/ROG-GL502VT/overview/
There is clearly written

SSD for superfast loading speeds
NVMe PCIe SSD gives you superfast data access speeds so you spend less time waiting. ROG Strix GL502 boots up faster, loads apps quicker, and gives you shorter in-game loading times so you stay immersed and focused on the game.

Don't stop at a blazing fast SSD. Equip your ROG Strix GL502 with up to a SATA 2TB 2.5' HDD for an abundance of storage space.

Stop playing with us!!!!!

No G-Sync option is not cons because there is GL502VY which has Gsync!

Hello,
Your review states, that there's no NVMe SSD support with this laptop. This isn't exactly true, as my model was shipped with this exact SSD drive :https://www.scan.co.uk/products/256gb-samsung-sm951-m2-%2822x80%29-pcie-30-%28x4%29-nvme-ssd-mlc-nand-read-2150mb-s-write-1260mb-s-300k-100k

and it works just fine.

HWiNFO screenshot:
(http://image.prntscr.com/image/baadefc497c8435ba26b4afec4c89a4a.png)
As you can see, it is the GL502VT:
(http://i.imgur.com/pl5FwcH.png)