Harbelth HL5plus

I am looking to replace a vintage pair of Spendor SP-1s and have been looking at Harbeth HL5 plus as they seem to be a more modern version of the Spendor.  I listened to a a pair recently and found the imaging and upper end quite beautiful, but found the lower end a bit lacking.  The retailer explained it away as the speakers had not yet been broken in,  Are there any Harbeth owners out there who can comment on the bass response?
I owned a pair of SHL5 (non-plus version) and found them to be as you described the "plus" version.  I've since gone back to Harbeth 40.1's as they are full bodied and far superior to the SHL5 in my experience.  If you are patient and ok with buying used, you can find a pair of 40.1's for around $7K.  Another speaker to consider that I've heard at a friends house on several occasions is the Verity Parsifal Encore, which is superior to SHL5's, is full range and can be found for around $6-$7K used. 
I have heard the SHL5+ many times at dealers and shows and they always have excellent bass- punchy and full of impact. Not extreme full range but satisfying nonetheless.
It does depend on many things though including break-in. My Harbeth C7ES3 took almost a year of listening before the bass stopped developing.
In addition optimized room position and quality amplification will be part of the picture but the speaker is fully capable. Look at the Stereophile review, the reviewer noted impressive bass extension.
HOWEVER- if you want a more neutral, more dynamic speaker with really incredible bass check out the Spendor D7. I demoed these a week ago and bought them on the spot. The technology of their dual flared slotted port nails the bass response- near full range deep, very well defined and detailed. Best reproduction of stand up bass I have ever heard in a speaker. Again though- break in, amplification and positioning all matter,
Also IMHO the Harbeth 40.2s bass is wooly and loose.  
I did see the review, but was surprised by what I heard at the dealer; he even had an LFD amplifier driving the speakers.  But they were fresh out of the box.  Definitely will need to hear them again.  Its interesting you mentioned the D7; as I am interested to audition them as well.  Sadly there are not many Spendor dealers nearby; will need to plan a road trip. I hear they pair well with my Leben amplifier.
Thanks for the feedback.

IMO, never bank on a speaker "breaking in" if you think you heard an aspect you didn't like.

That said...

I owned the Harbeth SuperHL5+ for a while, and have heard it numerous times elsewhere, e.g. stores.

Given it's dimensions and rated specs, I did not find it bass shy - it sounded very full throughout it's entire range (given reasonable expectations).  Of course if you place it nearer, say, the back wall you will get more bass re-enforcement.  But even well pulled away from the wall I found it sounded quite full and I wasn't thinking "this is really lacking bass."

They are fabulous speakers.  I sold them only because I felt I already owned speakers that did everything a bit better.  But whenever I heard the Harbeths, as I just did again last week in a store, I fall in love with that sound again.
Even though I own Harbeth, also check out the Graham LS5/8 or LS5/9. 
Those Grahams are a good recommendation.  Also check out the Spendor Classic 100 (less expensive than the H 40.2).
I own the SHL5+'s and adore them.  They are a bit power hungry, but as long as your amp has enough juice, bass shouldn't be an issue.  That said, I live in an older apt, and rarely crank it up too loud.  But the imagining is phenomenal.
These British monitors are very interesting and they are probably great. I’ve never gone there because I’ve been told they need to be be played at high spl for giving their best.
These British monitors are very interesting and they are probably great. I’ve never gone there because I’ve been told they need to be be played at high spl for giving their best.

I’ve never heard that about Harbeth. And doesn’t that kinda go against the “British sound”?
That’s what I like about Harbeth, is their ability to be detailed and stay coherent at lower levels—at least in context to the big ones. 

As you are working with a dealer, a home demo is in order.  That is the only way you will know what kind of bass response you are going to get in your room and with your amplifier.  The Leben is a low-powered unit and may not elicit the bass you need but you have to try.  I believe your amp has a bass boost on it, which may help the situation.  BTW, I owned the SHL5s for several years and found them excellent with my then-Naim setup.