Thanks, Flac, I knew you'd have excellent insights. In your Harbeth-owning days, did you own the P3esr monitors? If so, and if audio memory serves, how would you compare them to the LS50s? I own and like the little Harbeths, but all this enthusiasm for the KEFs has piqued my audio curiosity...
I did own P-3s; in fact, it was P-3s that got me interested in Harbeth to begin with. As I said before...I was a tried and true Dynaudio man to that point; and had the $8500 Confidence C1 Signatures in my Main rig. I tried P-3s for my Office system, and I was like "WOW"!
I liked them so much...I sort of started listening more in the Office, than in my Main room
I actually moved them into that room...because I had a sense they could still fill it (my Main room is pretty small...like 13x11); and they did, nicely. But...P-3s just don't have much bass. So I tried the 7ES-3s, and the rest as they say, is history.
As for P-3s vs. LS-50s; I would say it comes down to what music you listen to most. P-3s have that warm, woody...full, rich middle; even more-so than the KEFs. So...if you listen mostly to Jazz, Folk, Acoustic, Vocals; I'd say stay put, and enjoy. If you miss the P-3s, being able to keep up on Rock, or overwhelmed by complex passages; the LS-50s might be a good compromise. They're not quite as magical in the middle...but they do have more punch.
The other thing I'd keep in mind, is I think the P-3s are easier to drive. As I eluded to...I think the LS-50s need some juice, to sound their best. Hope that helps.