Image quality: SD Quattro low-res vs. DP2 vs. Fuji X-E1 (downsampled)

Tom Schum from the dpreview forum made a comparison between these cameras:
SD Quattro (low resolution 1:1:1 Foveon structure) vs. the original DP2 and the Fuji X-E1 (downsampled)

https://www.dpreview.com/forums/post/58888373

Some people claim, if you want true 1:1:1 Foveon quality with the sd/dp Quattros, you should use the low resolution mode. 

Lets have a closer look at 200%: (ignoring the Fuji)

    click image for full resolution:

The sd Quattro sample looks sharper. (probably different sharpening amount) 
But have a look at the red and yellow surfaces of the boats.
The dp2 looks natural, smooth and realistic while the sdQ is noisy and shows posterization.

Quattros shortcomings are evident even in low res (aka true 1:1:1 Foveon structure) which leads to the conclusion that the sensor itself is flawed. 

Additional information:

A new conversion from the sd Quattro image with luminance noise reduction set to minimum:

Posterization effect is reduced, noise/grid becomes more visible.