I know it's not going to be ideal.  Maybe the next step is to install a Connect Amp in one room to demonstrate sound quality to the client (and myself).  This is a vacation home so coordinating when the client is in town could take a while.

Impaqt - The SA3 amps have aux inputs, but these are only installed in 3 zones (other zones have SA2 amps without aux input).  The bigger issue would be operation.  It would be a nightmare to use the Bose remote to turn on the zone, then select the Aux input and then go to the Sonos app to select music.  Then there's volume control... you could lock Sonos to fixed and then use the Bose remote and volume control knobs that are also in each zone for volume but you loose the convenience of volume control through the app.  None of this sounds very applealing!

What's your basis for stating "Sonos Connct amps will NOT work properly"?  Is this just your opinion, or have you tried it before?  These Bose amps seem to work with a variety of different Bose Lifestyle speakers and there doesn't seem to be dip switches or anything else to set specific DSP for each speaker so I don't really think there is any "DSP" magic happening the Bose amps.  From an impedance standpoint it looks like the Bose speakers should work with the Connect Amp too... that was my biggest concern is that they might be 2ohm or some other weird proprietary configuration.