Anyone use Koetsu with Harbeth

The upper tier of Koetsu cartridges sound different from one another, at least to the point where it would be useful to know which Koetsu you have in mind. The commonly held conception about the mid-range priced Koetsu's is that they produce a lush midrange but lack bass oomph and can seem to sound a bit rolled off in the exteme treble.  Is that what you have in mind? If so, maybe mating such a cartridge with a speaker that had similar character might be too much of a "good" thing, if your aim is midrange uber alles.  But, as noted, that general description of a Koetsu does not hold for all of them, anything above Rosewood level, perhaps.

I was thinking koetsu rosewood signature or platinum...hopefully latter budgetwise... 

I ask about it because my current cartridge is lyra kleos and its wonderfully transparent in my system. but perhaps a little richer warmer sounder cartridge might suit me better....

However harbeth a bit warm so dont want overdo it....

I guess will try to convince friend who has koetsu to bring over one day when pandemic less prevalent and not on his TT to hear it on my system

The Lyra is not a romantic rich midrange for sure. I would roll some tubes in the phono stage long before I went cartrihunting unless of course it’s worn out.

disclosure, I run a Lyra but sold many and greatly appreciate Koetsu 

Harbeth's are typically a warm sounding speaker ( nothing wrong with that, IMHO). Koetsu's are also a warm sounding cartridge. The Kleos is more resolving- and if set up correctly, more neutral than any Koetsu that I have heard. 
I would think that for most the Koetsu/Harbeth match would be too warm and not resolved enough.

I recently did a search for a new cartridge for my system which includes Harbeth Super HL5+ speakers and the Aesthetix Mimas integrated amplifier. I use a Clearaudio Performance DC turntable. After listening to 10 different cartridges I settled on the AMG Teatro. It was the best cartridge I've heard at that price point, $2700. Based on the sound you are looking for it might be a great choice for you. There are a few reviews online that go into the specifics and may be worth a read.

 At $4K you might want to look at the Clearaudio Stradivari v2. It's a bit more rich in the midrange than the AMG. Good Luck!