My experience of smaller Harbeths is that they lack treble. A lot.
I don't have the C7s, so wasn't going to post in this thread, but I found this comment surprising. I like treble, and started out with (and still have) a lot of different Klipsch speakers.
I have the 40th anniversary Super HL5 Plus and P3ESR SE and neither are lacking in the treble department, at least in my system. The P3ESR in particular are revealing information in songs that I'm very familiar with that I never noticed was there before, often in the upper registers. I listen primarily to classic rock, but also Jazz, Classical, EDM, and more. The P3s don't have the body, weight, or dynamics of the Super HL5 Plus, but they sound more alike than different.