My intercom business has died the last year or so. We no longer install music intercoms (because everyone wants distributed audio). Now we just do Greyfox (OnQ/Legrand) if they want to talk from room to room.

We did do a replacement with the M&S DMC3-4 (the DMC1 is for new construction using Cat5 only). It is a nice unit, but the sound is terrible compared to distributed audio because it is mono only. We had some issues with the install because of room speaker size, etc. But for the most part was pretty simple.

If you are upgrading for sound, you would be better off looking into a distributed audio system, installed by a professional.