People confuse the terminology. 12 bit vs 13 or 14 is not really compressed! All Canon RAW formats are compressed, though usually lossless. That's what you want: lower file sizes while retaining all the information.
The lower bit depths aren't really compression. That's just not capturing as much information in the first place. Note that this only costs you dynamic range, and once your ISO is at or above 400, you will see no difference between 12-bit (Electronic shutter), 13-bit (12 FPS) and 14-bit (8 FPS or below).
See photons to photos for reference
With the lossy compressed RAW (CRAW) you are giving up something else. But nobody I am aware of was able to visually identify, what that is. But CRAW alone does not have to do anything with the 20 FPS mode.