I'm currently using 4 insteon icon switches (low-end quality, seem discontinued), a keypad, a PLC and a few icon appliance modules. Currently, the system is rock solid, but I had a few issues with the PLC. A firmware update solved the problem.

From what I understand, the system work best if you have a minimum number of items. At 5-6, I have no issue, but at a friend's house, he only got 2 and sometimes switches don't turn on. Both of us don't have RF-repeaters.

I had to return a defective item and it was assle-free. I paid return shipping, but got the replacement in no time, no question asked. Customer support was really good.

The PLC is OK, but the software isn't great. I currently use a few third party software and it's better. I will probably buy a PLM as it'll be easier to interface with a microcontroller.

Once you start with a product line, you're kind of locked with them. Insteon seems the cheapest way to go. You'll probably read comments that build quality is an issue, but at 45$ a switch, you can buy a few spares for the price of a single UPB switch.