I just registered in order to thank you guys a bunch for getting this thread going, and especially Zuri for his teardown video!
I literally got it done in 15 mins, with just some basic PC building experience, and I now get the expected 490/520 speeds with a 256gb 840 pro.
Some notes for those still on the fence:
- Using a guitar pick I got very good feedback from the feel of the cut. You really feel when the adhesive strips loosen and you just need to take it a little bit easy around the webcam, no problems here.
- I didn't loosen the bottom tape. Reason being I thought I got enough room to work without pulling the screen connectors. I just held the screen gently in one hand while undoing the speaker screws and hard drive with the other. This is in no way a recommendation, but if anyone was wondering, you can do it this way.
- Clean boot with no issues from the get go after connecting the ssd with a usb adapter and cloning the original hdd using Super Duper.
Now Ill just need the tape strips to arrive from ebay so I wont have to have two clams at the top of my screen

And btw, I am positive if you go easy with your screwdriver and wash your hands before touching the inside, you can get in and out unnoticed in case you would need to use the warranty. You will need to put the original hdd back in of course, but it really is a 15 min process once you know how to do it.
Cheers guys!