I did a quick google and found this: FAQ: Sending images to a computer (Wi-Fi function) (EOS 6D) which is a very detailed step by step procedure for transferring pics to a computer.
But I also came across this post: 6D WIFI: how long for RAW transfer?(dpreview.com) which references The New Canon EOS 6D – Welcome to the Full-Frame Club! which says:
6D boasts GPS receiver and WiFi transmitter. This is great, but, as rumored, 6D’s WiFi does not support transmission of RAW files, but is meant for sending JPG files and video clips to devices like smartphones, photo printers etc. This is cool to play with, and can be handy to review your JPGs on a PC tablet for example, but that’s it.
However the dpreview post has several people saying that this is incorrect and that you can transfer raw files. But there is at least one comment that says:
I was able to transfer through the wifi raw from the body to either my computer and my ipad 2.
However it's a huge difference in between the transfer speed with the usb cable and the wifi.
For a few photos it's ok but but for a large amount I still prefer the usb option.
Another comment from the dpreview post has hard numbers on what I suspected .. the process is slow:
In the tests I performed, going from the 6D to a computer running DPP (via WFT), with both devices connected to the same access point (running at N speed, and both fairly close, so let's say "normal" signal degradation) I was averaging 15 seconds per RAW (avg 24Mb in size) and 4 seconds for JPG, around 5Mb in size. This was timed from shutter click until it appeared in the DPP window. That was in the tether mode for shooting.
This delay may or may not be acceptable depending on what you are shooting.