I have used the SRaw (10MP) on my 5d2. They look pretty good, but noise is hardly any different and you lose many MP. I am seriously contemplating the 5d3 for several reasons: FPS, AF, high ISO noise, and bigger Sraw files.
I know the low ISO "banding" crap gets beat perpetually to freaking death. But it is a tiny flaw in Canon's sensor design. I'll take their awesome colors and low light ISO with this "banding" anyday. That being said, do the SRaw files render the noise any differently than standard RAW(on the new 5d3 of course) ?