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


.... what speaker did you buy? 
dhcod
If you like your speakers to make music, as opposed to just playing the notes, Harbeths are one of the better choices. Some people want their speakers to give them audio thrills; others prefer to listen to music.
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.