I'm buying a laptop in a couple of weeks and my budget is 1100€ max(This MSI laptop costs 1099€).

It will mostly be used whenever I'm out of home and can't access my main pc.

The laptop that I have had my eye on is the MSI GE60 (0ND variance) 15.6''. The specs(from the product info) are:
CPU: i7-3630QM
GPU: GTX 660M 2GB DDR5
RAM: 2x 4GB DDR3 (<-- Doesn't say speed, but I assume 1600)
HDD: 750GB 7200rpm
Screen: 15.6'' 1920x1080 Anti-Glare
Optical: Blu-ray
WLAN: 802.11 b/g/n

The laptop has 2x USB 2.0 ports and 2x USB 3.0 ports, also features a mSATA SSD slot.

I'm curious of the mSATA SSD option. Most laptop warranties are voided if you open the back so would my warranty be voided if I added the SSD myself or do I have to ask a retailer to add it either before or after receiving the laptop?
Currently the only mSATA SSD option I have is the A-Data 128GB XPG SX300 which supposedly has 550R/500W speeds.

Also all will be ordered from finnish sites(due to it needing to have Nordic(FI) keyboard), so the amount of products to choose from is fairly limited.