I owned both Spendor 3/5s and de Capos. I also owned Spendor 2/3s over a long period of time. I haven't heard the current HLP 3s, but did audition the older version 6 or 7 years ago. I have also heard other Harbeths in a home environment a few times. I strongly disagree w/ the above assessments. I would chose the Decapo over either of these in an instant. The Decapos are much close to full range, far more dynamic and extended, but still musical. Particularly w/ jazz or classical, these speakers can be eerily realistic in the right setup. The Spendors may sound more "magical" w/ voices, but you would be giving significant fullness of sound and resolution. Of course, the real comparision to the de Capos would be the 1/2s or Compact 7s/5s. I heard the 1/2/De Capo comparision a number of times with various amps & sources in a dealer's shop, and it is a very close call. I probably would have taken the 1/2s at the same price, mainly because my prior experience w/ Spendors, but got a good deal on a demo pair of De Capos. I replaced the de Capos w/ Living Voice Auditoriums, and much regretted the choice, even though the LVs are an excellent speaker that bests most in their price range. JMO, of course.
TLH