Here you are the differences - screenshots of actual .m2ts file, zoomed in with MSpaint, PNG pictures (click for larger versions):

test clip 3 (4000kbps)

test clip 4 (16000kbps)

just for the sake of comparison, bicubic uncompressed:

Now, maybe the second image has a bit too much dnr; but the difference between it and the first could be seen perfectly when magnified; then, if it could not be seen in motion, at the native resolution, is another matter... (^^,)

A second opionion is welcome!