https://www.highfidelity.pl/@main-1106&lang=en
the above review will help you
i have the 40.2/40.3xd as well as the sp100 r2, to me they are both truly excellent wonderfully coherent big monitors with similar personalities (easeful effortless natural presentation of the music with inner detail well integrated into the overall soundstage, excellent bass response, magical with voices and acoustic instruments)
harbeth is less efficient, a bit warmer/smoother, likes fine solid state amplification for best bass, sp100 r2 has a touch more forward treble and upper midrange bite, touch more air/snap, 2-3 db more efficient higher impedance, thus more suitable with tube amps than the harbeth
with proper system/component matching and placement i really don't think one outperforms the other
note differing tweeter placement on these two models, so stand height needs to be a bit different for the two