Spendor D9.2 vs. Harbeth super hl5 plus xd + REL Stentor III vs. Spendor Classic 100?

What krens0006 said above. The D7 or 9.2 would likely be all you’d need if you like a lot of detail. The Harbeth and Spender 100 a little less "aggressive."
Hold off on the subs (you need 2!) until you get the speakers. See how you feel then.

op

it would be helpful if you discuss what type of music you listen to and what you value most in terms of sonic characteristics of a high end hifi system

...and also if there is any ancillary equipment you intend to use, specifically, amplifiers

I don't really see the Spendor D series sitting comfortably with the Harbeth or Classic Spendor speakers.   The D series floor standing speakers are, to my ears, "Spendors" in name only: otherwise they are simply modern speakers and sound like it.  I don't find any particular continuity from their classic sound, no particular "Spendor magic" in the mids that sounds like Spendor.    Which doesn't mean someone can't like their mids of course...they just aren't the same.

The Harbeth and classic Spendors have at least something in common - that rich midband and classic box tuning which seems to give vocals in particular an organic presence, weight and roundness.

I owned the Harbeth SuperHL5 plus, and still own a little pair of Spendor S3/5s and even those share that similar trait.   I've been eager to hear the newer Spendor classic speakers but they are rare as hens teeth for audition.

prof +1  I heard Classic 100 and D7 in same system same day; there was no comparison, the Classic was so much better on all fronts.  I heard the SLH5 in a very different space/system, and found it a little bright.  Quite unlike the 40.2's that I ended up with.  I'd rank the 40.2 just a tad above the Classic 100.  Some people manage to put 40.2's in remarkably small spaces.  If you have a full meter behind from the back of the cabinet, and good space to both sides, I would think it could work.  The other speaker I would rank #3 was the Vienna Acoustics Liszt.

totally agree w prof on all his remarks ...  not that the spendor d series is bad...