Harbeth 40.1 vs Sonus Faber Olympia III

“much better” and “no contest” descriptors are frankly just not helpful

your preferences are just that, preferences, nothing more 

describing what you hear, explaining sonic differences, clarifying and comparing can help others understand and maybe help lead them to make informed choices; the ‘why’ of your preference is what matters, not simply the preference 

that said, my preferences in speakers now include aesthetics AND sonic presentation; as a result the SF brand is really tough to beat (IMHO !), they look and sound fantastic (Olympica lll)

I’d very much like to listen to a pair of Harbeth speakers but based on looks alone they would never find their way into my living room, I much prefer the looks of the SF product 

I’m very much interested in the sonic differences between the 40.1s and the Olympica lll’s, only because both are very popular and learning more about the hobby makes it more fun, not because I’m considering a change 

this I know; without sufficient power and room to breathe, it’s just not realistic to think you’ve heard what the Oly lll’s are capable of; 150 Pass Labs watts were not enough in my experience, once I upgraded to the X250.8 the SF’s literally came alive 

I had an opportunity recently to demo the Sopra 2’s which are often included in lists of considered speakers in the price range; couldn’t live with them.  Aesthetically no comparison vs the SF product, and far too bright sonically, IMHO! The Oly lll’s are coherent, smooth, dynamic, detailed, and cast such a huge soundscape they just captivate me.  A comparison with the 40.1’s would be interesting.  

I've heard Olympica II's at one store, and H 40.2's at another.  The SF was a modern, competent speaker, that didn't really distinguish itself from half a dozen other similarly priced makes/models.  The Harbeth is something very special; lots of people like them greatly, some don't.  I'm with the majority opinion in this thread, but as always, YMMV.

Again: why?   Details please! 

I have had 40.1's in my room for the past two years.  I love them more than any other speaker I have heard.  But, yes, it's always personal preference.  I find them to be the most natural sounding speakers I have heard, but they are not dramatic in their presentation, so some folks might not like them.  They sound best with classical, jazz and acoustic based rock.  Loud rock with kick drums and heavy bass are not the best on the Harbeths, but still listenable.  
Also, contrary to what some will say, amplification choice is really important to get the most from them.  I love tubes, but now I am using a Lyngdorf TDAI-3400 with them and I believe this is the best I have heard these speakers sound.  200W/channel into 8 ohms is an adequate amount of power to provide the right amount of finesse and slam, at least in my experience.  My room is not as big as yours, just so you know.  I had them in a bigger room this summer and thought they sounded even better than they do in my regular listening room, so you should do well with them in your room.  
I'm sorry I cannot directly compare them to the Sonus Faber speakers you are considering, but I have heard SFs at my local dealer and found them to sound wonderful.  They are also gorgeous to look at, which I understand to be important to some folks.  I would just be careful about disqualifying a speaker purely based on its looks, however.  I personally find the 40.1's lovely to look at, especially without the grills.  
Enjoy the hunt, and best of luck in your decision.

What are the Harbeth 40.1 and 40.2 differences ?