JA Pulsars vs Harbeth 30.2

Both Harbeth 30.2 and JA Pulsars are excellent speakers but they’re not going for the same buyer profile IMO. 30.2 is more of a monitor speaker and has a distinct sound. I would never advise anyone to buy the 30.2 without listening. You will either hate it or fall in love with it. 
 

Pulsars are more traditional in the sense that they will sound more similar, but overall much better, than your existing speakers. 
 

Having said that, given your room size why are you looking at bookshelves? You can easily accommodate floorstanders in that room. 

One more thing, Harbeths will never sound thin. Whether you like them or not, one thing they’re not is thin sounding. 

I've heard the Pulsars many years ago but they burned a very good impression in my brain, was very impressed (although don't think they are made anymore). Harbeths are very soft sounding IMO not my cup of coffee.

Harbeths need a beefy amp to drive them. If they sound thin or soft, usually because the amp is not powerful enough to drive them. But yes compared to Joseph Audio or Focal etc, they’re not treble-focused.