I've found some HD clips of the 3D BD on youtube; the colors, indeed, are better than what I thought at the beginning... watching a clip instead of screenshots revelals more things.

So, I downloaded two clips (T-rex and Gallimimus) and compared them with my PAL laserdiscs, just for fun.

Here you are my conclusions:

laserdisc is less cropped than 3D BD
obviously laserdisc has less resolution, but it is not that bad - it seems that the 3D BD has less resolution than what could be achieved by a BD, but it could be due only the youtube compression
3D BD is darker in comparison
in the T-rex scenes, a lot more things could be discernable in the dark in the laserdisc, while the 3D BD seems to have more natural skin colors
in the Gallimimus scene, the grass and the sky in the laserdisc have "pumped" colors, but in the 3D BD the clouds are pinkish...
...and the 3D BD CUT MORE THAN SIX SECONDS the scene where the T-rex tears apart flesh from a gallimimus...

I was not aware that the 3D BD has scenes that were cut... I mean, six seconds are A LOT in a single scene, guess how many other scenes are cut, and how much time is "lost" in total...

My PAL DVD is not cut; what about the 2011 BD?