I don't know why you'd need an SSD of that large a capacity - I'd keep big files on the HDD or if I ONLY have an SSD internally I'd put those large files on an external drive
I am nervous about recommending a drive because ASUS laptop specs & internal cards vary from region to region. You might get that SSD drive & find you need to fit a card to run it. I looked at the Amazon.com version of the ROG G752VL & it is described as "2.5" SATA3 2TB HDD
7200 RPM with 256 GB SSD [M.2 2280]" - so it seems you can get it with the faster HDD or it's an error...
I downloaded the English version manual from ASUS & on page 98 it explains how to fit an M.2 card & it says "the M.2 2280 slot does not support M.2 SATA SSD" I have no idea what that means in terms of what SSD it DOES support. I think you should chat with ASUS & ask them what card & SSD is compatible - give them the exact model name, number & the SKU next to it. You might want to think about if the 7200 RPM is a better option or if you can get that ASUS only with an SSD fitted. I would not buy until you've looked at other suppliers with the components that best suit you. Don't rush into it.
I got the pdf format manual from here [it's not very detailed with no part numbers] & it's clear that fitting cards & SSD is very easy:
http://dlcdnet.asus.com/pub/ASUS/nb/G752VL/0409_E10716_G752VL_VT_VY_C.pdf