I can personally verify that the samsung 950 PRO m.2 ssds work quite well in the laptop. I currently have 2x256gb 950PROs installed, with the newest bios and RAID 0, performance is approximately 4200MB/s read, which completely maxes out DMI, meaning this is literally the fastest this laptop can read from a storage device.
I highly recommend even just one, for $177 you really can't go wrong.
That said, I suggest getting yourself a thermal pad to put between the heat spreading plate and the ssd. The gap is 1.5mm, get a 2mm thermal pad and you won't have issues with thermal throttling.
Tips:
1. If you aren't going for RAID, just use the samsung transfer program to move to the SSD, it'll be a lot better
2. Again, without RAID, use samsung's 950 pro driver
3. If you wish to use RAID, get intel's Rapid Storage Technology driver files and put them on a USB drive for installation of windows, as a reinstall will most likely be necessary (it was in my case).
4. If you're going with RAID, change the controller to RAID mode in the bios under the "Intel Rapid Storage" menu, then go to the SATA devices menu, switch the drives to RAID mode, and then switch BACK to the "Rapid Storage" menu to create the RAID device. In there, select defaults, 16kb is a really good overall stripe size for performance across different block size transfers.
Good luck! Let me know if you need any help. I try to check this account fairly regularly.
