Just purchased my first SP13! Which Ram will work in my new latptop?

While my new comp is being shipped to me I wanted to buy some low voltage ram to stick into the computer. I'm pretty technically savy, but I'm not a pro and I was looking for some help in deciding which ram works best for me. I only have the 1 slot open and I believe the laptop supports 1.35v ram.

Is having 12 gigs of ram worth it? Newegg.com - Crucial 8GB 204-Pin DDR3 SO-DIMM DDR3 1333 (PC3 10600) Laptop Memory Model CT102464BF1339

if not, which one of these works the best.

Newegg.com - Crucial 4GB 204-Pin DDR3 SO-DIMM DDR3 1333 (PC3 10600) Laptop Memory Model CT51264BF1339

Newegg.com - SAMSUNG 4GB 204-Pin DDR3 SO-DIMM DDR3 1600 (PC3 12800) Laptop Memory Model MV-3T4G3/US

 

I have this on my S13P:

http://forum.notebookreview.com/sony/680582-ram-upgrade-s13p.html

Pricey, but works. I've read somewhere that the Crucial 8GB low voltage DIMM throws up errors in memtest. I have no experience with that, but I played it safe and bought the OWC module.

 

Just FYI: there is absolutely no need to use Low Voltage memory.
Actually you won't be able to measure any battery difference too

 

I went with that not because of power savings, just being anal since the ones soldered on board are low voltage modules.