I owned the Harbeth Super HL5+ speakers and I had a number of serious auditions of the Devore O speakers to decide if I would buy them.
I absolutely loved the Devore O/96 speakers! I also love Harbeth speakers because both give more richness and body and organic tone to music than most other brands I've listened to.
The difference to my ear is that the Devore O speakers are sort of like Harbeth on steroids, or Harbeths on "speed." They are more lively, up front and dynamic sounding, and to my ear even somewhat more rich and full.
I've rarely heard a drum set sound so real as I did through the Devore O/96.
One way they are different is in the bass, though. The Super HL5+ is very even and linear sounding from top to bottom, which is wonderful.The Devore O/96 bass performance is more of a "like it or you tire of it" kind of thing. It's bigger, bolder, rounder, roll-across-the-floor-and-feel-it bass, where the bass of the Harbeth sits back evenly behind the speakers with all the other frequencies. The result is, for me, that Devores have more impact, and I feel the rhythms of the bass and drummer more than the Harbeth. They party a bit more, and feel a bit more exciting, and of course they go obviously lower in the bass than the Harbeth's as well.
Set up I think is more tricky for the Devore. They need good room to breath, especially from the back wall, so they don't overwhelm a room with their bass. And even at it's best, there are times when the Devore's bass can feel a bit overdone. But for most material: wow!
Both Harbeth and Defore have a clear, open, organic "wood sounds like wood" tone, yet both remain relaxed and unfatiguing, so they share that quality.
You say the Devores didn't sound as hefty or lush as you were expecting. I'm not sure what you were expecting, but yes their squat look suggests a beefy old-school sound, and they are actually more linear and controlled than you'd expect, so I can see what you mean on one hand. On the other, if they actually didn't sound rich and substantial, something was wrong, because one of the O/96's defining tonal characteristics is a richer sound with bigger image sizes and more body than the average speaker. That's what attracted me to them in the first place, and was consistent when I heard them in different rooms.
I ended up buying Joseph Audio Perspective speakers because they are great too, and fit my room situation better.
If you want to go down a rabbit hole, I did a long thread on my auditions of the Devore speakers among many others, here:
https://forum.audiogon.com/discussions/contemplating-devore-speakers-and-others-long-audition-report...