More RAW samples from DPreview:
Overall, just subtle improvements over the 18mp sensor.
Dynamic range (DR) is still behind Sony/Nikon (e.g. D7100) but ISO/noise is on par.
One thing to note is that the 70D renders colors the same way as the 6D.
Probably both are using new color filters compared to previous models.
As a result, colors are actually more accurate (albeit appearing somewhat less punchy).
Actually the 6D scored the lowest ever for a DSLR on the metamism index score at DxO for natural daylight shooting which would imply the most color-blind, least color discrimination of any DSLR.