The same speaker will perform differently depending on the front end. My Hegel H300, has a very musical bottom, works great with the Sopra, which extends down to 28HZ. Not a lean speaker at all. As a matter of fact one my daughters Kanye CD's shakes the house.
I have learned blanket statements are never accurate especially with speakers.
I haven't demoed a Harbreth with my Hegel so I cannot comment on how it would compare. I did listen to a nice pair of Harbeth speakers at AXPONA, a very nice speaker indeed.
At this level one really needs to demo as much as possible to come to an accurate conclusion.