Hello,
The way I look at it is Elan is the piece that ties all of the sub-systems together. You need to have your lighting, hvac, security all in-place before integrating and Elan system. Another thing to watch out for is that the subsystems are compatible with the Elan system. I am currently running an Elan HC6 that ties into and HAI system for security and hvac, Lutron Radio RA2 for lighting and shades, and Cartell for the driveway sensor. Recently, I installed the new S1616A amp and it is amazing. It supports both mono and stereo and you can configure any speaker for any zone-totally customizable. We have an iPad docked to a on -wall launch port that we use to control the house. In addition, the HR2 remote is awesome. It is wi-fi based and is always ready as soon as you pick it up. Let me know if you have any other questions.
Thanks!
-Joe