I think @ggbutcher meant that he currently uses dcraw to convert from the dcraw matrix camera input profile to a dcraw output space (the “-o #” options), and then makes an ICC profile from the dcraw output space, for actually editing the interpolated image.
As far as editing in “camera RGB” I find this to be very useful for certain purposes, including setting different white balances for different portions of mixed lighting images, using layers and masks to choose which white balance is applied to which portion of the image.
I think this “multi-layer/multi-white-point/mixed-lighting” approach probably works for any camera input profile. But it’s easy to make a custom camera input profile (http://ninedegreesbelow.com/photography/well-behaved-camera-profile.html) that’s also a well-behaved (eg neutral gray axis, with white=Lab 100,0,0 and black=Lab 0,0,0), that can be used for other types of edits.
However, as @houz notes, using “camera RGB” can cause issues:
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For editing operations that are chromaticity-independent, as long as camera RGB is also a well-behaved RGB working space, then these operations produce the same results regardless, assuming no precision losses from editing in such large and oddly shaped color spaces.
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For other operations, well, it depends. If the goal is to retrieve individual channel information as captured by the camera, use “camera RGB”. If the goal is to split-tone using Curves, this operation is likely to produce unpleasant results in “camera RGB”, as will making single-channel gamma modifications.