People That Have Upgraded From Harbeth 30.1s....

Just now sold the pair  via CL   for $2500 , what I paid for them .
In the future , I can see having a pair of the 40.1 
, as long as I can sell them for the same price as I purchased them for

@dromme

“BTW , I can make my Klipsch sound very much like my Harbeth by placing a towel or light blanket over the horn .”

Everyone is entitled to their own opinion and if you prefer 25 year old Klipsch speakers covered with a blanket or towel then more power to you. What kind of gear are you using to drive your Klipsch speakers? What gear were you using to drive the Harbeths?

For me and my ears, I would prefer Harbeth anything to Klipsch anything.

lol ,   well , okay , then

I owned the M30.1's for 6 years and sold them after comparing to the similar sized ATC SCM19 mk2.

The ATC has a more neutral and dynamic type of sound, while still having wonderfully natural mids and highs. The SCM19's bass range is significantly more taut and punchy and - while the specs don't indicate it - reached lower in my room. Sounds more tuneful in the lows too, probably due to the sealed loading vs the ported cabinet of the 30.1's. The ATC sounds much more comfortable with bass driven music and at high SPL's too if that is your thing. They don't give up anything with vocals or acoustic music, though a less plush sound than the Harbeths. 
Both very nice speakers, but I prefer the SCM19 by a significant margin.

Worth noting that while the SCM19 has similar sensitivity specs to the 30.1 it sounds (to me) about 3dB less sensitive. Where a 50W amp might be fine with m30.1, 100W plus would be preferable with the 19's.