Get Canon 5DS DSLR at B&H Photo.
Presented in my review of the Canon 5DS R, I show that sRAW is not at all like mRAW in per-pixel acuity:
The analysis includes the full-res raw image downsampled to match sRAW resolution.
Also added is a discussion of RAW, mRAW and sRAW file sizes:
The user of the smaller formats for saving space is a marginal idea.