This can be done, without a lot of major surgery to the house.  The DIN module's from Crestron will work in the lighting cans from Colorado V.net.  I went to school in Loveland, CO for this system and installed quite a bit of these back in the day.  The communication protocol for all of the v.net equipment is over Cat5e and used the CAN Bus protocol.  The backbone of the system was linux as well.  Everyone here is right about the inability to get parts from obsolete/manufacturer when the items fail in the system.  If this is in Colorado, I am here as well.  Give me a PM.  I would like to go on a site walk and let the client know his options moving forward.