How does the technology for shabas-compliant voice amplification referred to on this architecture firm's website work? Is it different technically from a regular microphone setup or is the distinction an aesthetic one (although I guess when it comes to acoustics the line between the two is quite blurred)?
If I understand correctly, they're offering two options:
For the traditionally-minded, they can just modify the room in some ways that will make unamplified voices carry better (e.g. the right materials, the right angles, occasional some holes in or pipes in surfaces); I can't see anyone finding anything objectionable to this (though it may be expensive, and may not always work with the existing layout/construction of the synagogue).
The other option they're suggesting is a "Sabbath-friendly" microphone, as developed and endorsed by Zomet (pronounced "Tzomet"; an institute for the integration of Halacha and technology). Ask your local rabbi whether a "Sabbath-friendly" microphone can be used.
From what I understand, there are two designs of "Sabbath-friendly" microphone out there right now.
Again, this is assuming I understand their description accurately.
My impression is that the Sabbath-friendly microphone has caught on far more in Israel than it has in America. I recall hearing Rabbi Rakeffet tell his students that if they're okay using one, it can make the rabbi's job much easier on his throat. It might be interesting to look at Rabbi Moshe Feinstein's responsum banning conventional microphones, and see how the above designs would be allowed/prohibited according to his reasoning.