I have shot the 5d3 in ISO 25,600 and while the jpeg is very useable, I cannot get the same level of clarity from the RAW using Adobe CR noise reduction. I can dial up the NR more, but then the image gets much softer than the jpeg.... OTOH, if I apply slight amounts of NR to the jpeg, it gets very clean and clear as well...
Kind of a mixed result since I love the flexibility of exposure control in RAW...
Disclaimer: I have not tried CS5, Topaz & NIK NR on the RAW's yet... Just LR4