Well not everyone's priority is the sort of speed and dynamics the little AE1s could muster. At the expense of sounding rough in certain situations.
I'd probably use an amp with some notably obvious transient capability with any Harbeth to wake them up but that is just me. They are a bit too laid back and slow for me. But they can sound very pleasant indeed.
That said I am thinking of the larger models and it does sound like the P3ESR doesn't suffer so much in this area.