Harbeth are one of my favorite speakers (I owned the SuperHL5plus for a while). I’ve heard the 40.2s a couple times and recently got a nice audition of them at a store (in a big room).
Before I put on my tracks they played a track with a female singer accompanied by a muted trumpet (and I think maybe some light drums?). I was taken aback! It was probably THE most 3 dimensional, corporeal imaging I’ve ever heard! The singer seemed way back in the "stage" but fleshed out, properly sized and, well, corporeal and dense. When the trumpet entered off to the side, same thing. This big round, tonally convincing trumpet just appeared. The Harbeths have a way of making many other speaker imaging sound flattened and lightweight.
When I threw on a bunch of my tracks there was more excellent soundstaging/imaging - a really big sound. Though I was finding the bass a little pudgy. (Maybe the big room worked for the big soundstaging, but somehow against the bass control?).
Generally it all had the nice Harbeth richness, roundness and weight, with nice accurate-sounding tonality. Though for whatever reason I wasn’t finding myself totally seduced by what I was hearing. There was a bit of a polite, reserved quality to the sound, where it sort of "sat back behind the speakers" in terms of staging and not being tonally forward.The Thiel 3.7s I owned (and to some degree my 2.7s) gave me a lot of what I heard with the Harbeths in terms of image size/weight (though not as much), but with a bit more energy and toe-tapping quality.
My current Joseph speakers also do a great job with bass-driven music, with a reach-out-and-grab-you bass quality.
Still, the 40.2s are one of those speakers that I want to spend more time with some day. Ultimately they don’t really fit my room aesthetically and practically. But they sure have some special qualities that separate them from the pack (in terms of what interests me sonically).