As I'm trying to avoid doing house chores today, I've 'escaped' into researching some more about home automation systems.
So, maybe of interest to someone, hereby some basic comparison info of the various RF systems.
Nice introduction comparison of KNX/RF versus Z-wave and Zigbee. It's a bit dated (2006), but still ok:
Cost comparison between the various home automation systems. See table 5.2 on page 11. Also a bit dated (2007)
smart-a.org/D3.2%20Communication%20Cont ... iances.pdf