A couple of days ago I bought a nr mint pair of Proac 1.5s (dating from 2001) and they are sounding great. I have come from having owned Harbeth speakers so thought you might be interested in a brief comparison of sorts.
A couple of years ago I had my dream speakers, Harbeth SHL5's. When I heard them at a dealers I fell in love with their big, open, natural presentation and winning way with voices and piano especially. Anyway I bought a pair initially driven by LFD Zero LE III (sweet and punchy but a little light weight), then Luxman 505U (great amp, but eventually found treble a bit hard for classical) and finally LFD NCSE (love it and still have it). The SHL5 is just a fantastic speaker but space restrictions meant that I had to regrettably downsize. The obvious choice was Harbeth P3ESR and I had a pair for a few months. Their midrange is really quite beautiful but in comparison the treble was just so so (to my ears - others seem to love it) and moving from the SHL5 the change in sweetness and extension in the treble was obvious. I also found the bass at times a bit tubby. Anyway, I sold the P3ESR's, which I thought I would never do.
So, and now I am getting back to the point of this post, I needed new speakers again but was short of funds so as a stop gap I bought a pair of new, end of line, Proac Response Satellites (I think these are basically the Hexas in new cabinets). Overall I have preferred them to the P3ESRs (they actually have very similar specs on paper) - no they don't quite have the same midrange magic, but they are sweeter on top and seem more balanced overall.
With my positive experience of the Proac Satellites I took a punt on a pair of Response 1.5s that came up at a good price. I have been playing them fairly continually for a couple of days and am very happy with the sound. What I like about them is that they are very balanced and play all genres equally well. I read a review somewhere that compared Harbeth 7es3's to Proac D25's and the presentations of the speakers was described as being quite different. Though my 1.5's couldn't be mistaken for SHL5's they are not so completely different as online discussions would have led me to expect. So perhaps these 1.5's are a touch warmer than the D15s and D18s that replaced them? What they share with the SHL5's is a low fatigue, listen-all-day quality. They are working well in a small to medium sized room quite close to back wall. So that's enough ramble. To summarise I think these are a very good value used buy given that its current successor is now priced over £2000.