Interestingly, before ordering S400 mk ii, the other two bookshelfs I had in mind are Special 40 and Confidence C1. I went through various reviews and the demo tracks and chose the S400 mk ii. From the tracks in the video listened with quality earphone, the bass from S400 is better suited to my taste, weightier and equally punchy and quick with Special 40. If you tune into 8:30 mark in the video clip and listen to "Drum Solo", you know what I am saying. However, that punchiness seems to disappear in my room. BTW, I have been auditioning it for more than 30 days and at least put in 150 hours of listening, not to mention I purchased a used pair.
However, I do agree with you for all other characters such as SS, airiness, etc.
https://www.youtube.com/watch?v=JQgycQbDNE8&t=648s