Thank you JavaLawyer of your response.
It is funny that you responded with the exact same response 1½ months ago. At that time the cameras were not accessible to me. Now I got into the DCS-2132L as well. It seems to work the same as mine. I made a lot of picture quality tests, a bit like with mine at home.
The problem is that A) there is no darkness, and B) there seems to be lots of IR illuminators around (other cameras and even other strong IR sources!) . But thanks for the link, it really did give me something new to ponder.
I also found out two new sources:
http://www.youtube.com/watch?v=NLQ0QvpS3sY
and this from this very forum
http://forums.dlink.com/index.php?topic=53657.msg207479#msg207479
(The latter I had seen, but didn't know it was 2132.)
This last one is unknown how dark it has been.
But anyway any of these are WAY better than my night vision. Even with (slight) external illumination, TrackIR5, the night mode visibility is really blind. In best of controlled situation my camera shows only 10-20cms, close objects on the same table.
So, I'll have to take and RMI it. I hope the above information might help anyone else asking the same questions. I'll take new pictures yet, and store them here for reference, before I return it.