Thanks
@new entry and
@plakat for the feedback.
I stumbled across this video, which is of course a bit far-fetched due to the lack of information about the recording quality, editing and changes due to the YouTube algorithm:
However, assuming that the recording itself is coherent throughout, I think the reduction in background noise (highs) is indeed quite noticeable when the Composer is placed on the dummy head (for comparison, the new Grell headphones seem much more open and less attenuated, video in the same channel). So even this slight attenuation is promising, as I am often disturbed by external noise in the high frequency range (buzzing, humming, rattling of the plastic keyboard, clicks, etc.).
Anyway, the discussions and comparisons here in this thread, especially with the HD800s (a pleasure to mix vocals with) and the Hifimans ("Schönfärber", which I sometimes like), and the possibility of somehow getting more "excitement" than with the sometimes too perfectly balanced DCA Stealth, have now convinced me to order one today. Hopefully it will arrive before the weekend. Let's see how I get on with it.