In correspondence with Harbeth I am understanding that the 40th Anniversary brought bigger changes to the 40 and SHL5 series and smaller changes to the series below. For the XD line the 40th Anniversary were continued with no real changes in the upper 2 models but brought the smaller speakers up to the same level. They simply couldn’t keep renaming the speaker after the 40th Anniversary to the 41st etc so they brought out a .3 or XD. The only change in the 2 biggest speakers is the loss of the bi-wire capability from the SHL5+ to just two WBT posts. I have the bi-wire-able 40th Anniversary so no need to upgrade within the same line since they have the radial2 drivers, better crossover and the WBT posts.
