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

I find Harbeth speakers, generally speaking, to be very well balanced.  For me they do a nice job across a wide variety of music.  Really big rich recordings sound rich, but not overly so.  Thinner recordings still have some juice and still sound good.
I remember concurring with a reviewer who said something like "With the Harbeth, everything is presented at the correct level.  Mixes sound right." 

I can't think of a single voice in audio today that speaks with as much clarity, logic and common sense as that of Alan Shaw.

Many, many times I was taken aback by what he had written on the HUG website, only to later find out that he was right...

https://www.harbeth.co.uk/usergroup/

dhcod,

You mentioned,
" I like my 30.1s but I want more of everything! More bass for sure. More dynamics too. A bigger image."

The M40.2  might be a good a very good option for you, considering you like your M30.1 speakers. 

That is the exact upgrade I made.

You will get more of everything including a more extended defined bass, dynamics ,  imaging ,  larger soundstage and most importantly ,a complete full range sound. 

The M40.1 is also a good speaker. A used pair of these could be a good choice for you.

 The M40.2 is more efficient ( easier to drive) , room friendlier and more transparent than the M40.1 though.

The Harbeth's are a good enough speaker to easily decipher the difference between entry level and a $2,000 integrated. If he suggests otherwise, he is selling the speaker short. Cheers -Don

Thanks @timo62. The 40.1s or 40.2s are clearly where I'd go if I got a big raise but was still forced to stay in our small home. If the raise was big enough for 40s though, we are likely moving and then I'm buying original Quad ESLs. My interest has been piqued by the suggestions that were in the $4-6k range on the used market. Lots of thing to listen to. I demoed SF Cremona Auditor Ms which are nice speakers but not better speakers.