I'm new to canon systems and I wonder what's the big deal with sRaw1 and sRaw2? I know Raw by nature itself, since in Nikon I shoot in Raw. In canon systems, they have these 3 types of Raw, what are their differences?
It is just the level of reduction applied before saving the RAW file. RAW is full quality, sRaw1 and sRaw2 downsample the image to make smaller files and save space on the card. The only difference is the amount of downsampling (thus lower resolution) that is applied.
Update: from comments, it was pointed out that it may not be simply downsampling, but it is a smaller file. I was only able to verify that the size of the file is reduced by discarding information. I was not able to verify what exact measure are used in the reduction of image data.
This really is just a case of reading the manual!
The different raw modes contain all the same properties as regular raw files, except at lower resolutions.
What resolutions those are varies by camera. For example, the Canon 5D Mark III has mRaw which is 10 megapixels and sRaw at 5.5 megapixels. On a 60D they are 10.1 and 4.5 megapixels respectively.
You can use these raw modes when full resolution is not required and you wish to store more images on the memory card.