I use Sound Anchors with my P3esr speakers. The stands helped focus the sound and improved imaging. I changed out the floor spikes with round headed carriage bold to avoid punching holes in my composite vinyl flooring (selected for acoustical damping; the flooring is on solid concrete). The speakers sit on small sorbothane pads on the corners. With the carriage bolts installed I can drag out the speakers for a near-field experience when I want to, which increased involvement at the expense of a slight inconvenience.
I would recommend open-frame stands for all the other Harbeths, but the P3s work great on the solid stands.
Do different speaker stands can really make a big sound improvement?
I am looking for stands for my new Harbeth P3ESR XD speakers and wonder how much improvement one can actually hear between close to a $1000 stands and a $100 one filled with sand?