Quote Originally Posted by Jeff Lucia
Shooting in raw, I don't think the camera applies a white balance value to the image, but it does record the white balance as data, whether you set it manually or it was in Auto mode. Then, when you convert the image on your computer, your raw converter typically applies whatever value the raw file tells it to.You can change all of your images from one location to one value pretty quickly using various raw converters, or even in Photoshop.

You're correct that if you shoot in RAW, you can change the WB in post \-processing without penalty. But if you aren't using DPP for post-processing, you might be losing some data if you shoot with a Canon flash. The flash passes color temparature information to the camera, which I think is stored separately in the RAW file from the WB, but used by DPP when selecting Auto or Flash WB. On a shot where flash was used, when I set Flash WB in DxO, it's a fixed 6000 K, but Flash WB in DPP is not a fixed color temperature, it varies by shot based on the supplemental data in the RAW file, which other programs ignore (along with things like AF point, etc.).