I am going to sound like a broken record with my speaker recommendations, but hear me out...
I would talk to this customer about Triad Speakers.
They use the best European drivers from Scan-Speak and SEAS, just like Sonus Faber. In fact, the Triad Monitor and Mini-Monitor models share the same sliced paper Scan-Speak midrange driver as the models ion the Cremona line, which is a step above Concerta in the Sonus Faber heirarchy.
The Concertas use the concentric ring tweeter (aka the "nipple" tweeter) from Vifa, who are Scan-Speak's little brothers in the D-S-T family.
The Gold Monitors
[Link: triadspeakers.com] use the flagship Scan-Speak concentric ring tweeter, which is CONSIDERABLY more detailed, and more expensive, than the Vifa version.
Paul Scarpelli at Triad jokes that that tweeter costs more per unit than their massive 18" cast basket Platinum subwoofer driver!!
Once the driver story piques his interest, talk about the Triad's unique position to be able to offer InWall versions of that same model with the same drivers, the same point-to-point hand-wired crossovers from audiophile components, the same heavily braced and damped enclosure...
The Silver Monitor is an excellent example, they make that modlel in FOUR different configurations for use on stands, in cabinetry, in walls, and as a directional in ceiling speaker.
[Link: triadspeakers.com]The InWall models are re-engineered with shallow depth and a flush grille for an InWall application...
[Link: triadspeakers.com] for 2x4 framed walls
[Link: triadspeakers.com] for 2x6 framed walls
The InCeiling model is re-engineered with a 45 degree baffle and a flush grille for directional placement in a ceiling.
[Link: triadspeakers.com]NOBODY at ANY price can offer the kind of application solving solutions that Triad can.