sRGB pre-clips the values in the image-file to correspond to small-gamut generic monitor and printer colorspaces. However, if I want to manipulate the output of the RAW converter further in Photoshop, I use ProPhoto because it keeps more of the high and low values as compared to sRGB, so there's not as much posterization and color-shifting of brightened shadows or dimmed highlights.
sRGB Export Histogram
ProPhoto Export Histogram
CameraRaw to Photoshop
Posterization of sRGB after Levels and Saturation Boost
Posterization of AdobeRGB after Levels and Saturation Boost
Smooth ProPhoto after identical Levels and Saturation boost