Harbeth 30.2 XD Vs Triangle Magellan Duetto 40th anniversary

My final thought:

If you choose the 30.2XD’s and feel a subwoofer is preferred, I would strongly recommend the model I went with . It bested all contenders and pretenders at the up to $5K strata price point.  It is seamless 30.2XD extension integration and disappearing act using high-end speaker cables inputs with a class-leading tight bass with a sealed bottom-firing design.

https://atc.audio/hi-fi/loudspeakers/subwoofers/c1-sub-mk2/

Good to know, @akg_ca!  Thanks very much.

It looks like, for a variety of reasons (aesthetics, cost, performance, ease of availability), I am headed to choosing between Revel Performa 226Be or ELAC Vela VFS 408.2. I do have a little REL T/7x in that space that connects over (i think) a proprietary wireless frequency (not WiFi, as I understand things) to the amp via the REL Arrow unit); and as i can’t have cables running around in that room and there’s no room for a bigger sub, i think that set up for the sub is the best i can do. (At least for now.)

@kirkwallace - I'd suggest auditioning those Revels with your amp since their beryllium tweeter can be a bit ruthless with Class D amplification, similar in that respect to the Triangles.

Good point @bill_k    
The dealer had them hooked up to a slightly older  Class D NAD that’s  meant for home theater, but still pretty comparable sonically to my c399.  The C399 should be a little more neutral if anything.  
Those Be tweeters are bright and assertive for sure.  On the whole they sounded ok to my ear — I’m used to ELAC JET tweeters —  especially once one was >8ft away, as we will be most of the time.  The whole sonic presentation was very good though. Such seemless transitions from lows to mids to highs. (I’m more used to 2.5 way speakers; I felt like the dedicated midrange driver was a really nice feature for these, and the base extension was ex excellent, without a sub even.  
I’ll have them in my space tomorrow so fingers crossed! 

Good luck @kirkwallac, hope you find your grail!