Infrared Repeater

[Steve]

I'm wondering if anyone here uses an infrared repeater. In my setup (pics in my gallery) components not on the top shelves don't always receive commands from my Harmony One due to my coffee table blocking the line of sight. I was thinking of using an IR repeater like this one. However, sitting on one end of the sofa or the other determines which components don't receive signals. The question I have is if I use one of these, is it possible that my components would sometimes receive "double commands" (a command from the remote and a command from the repeater at the same time) and therefore get out of sync with my remote? Or would I need to reprogram my Harmony so that all commands go through the repeater? Or do the little IR emitters block the IR port on the component so that it can only receive signals from the repeater?

One last question: The particular unit I linked to has this warning in the specs:

Careful consideration must be used when placing the IR Receiver near a Plasma Display.

I have a plasma display. What's the concern when using a repeater and how far away from the display would it need to be? I will not be using the repeater for control of the plasma display because it's high enough that it always receives remote commands without a problem.

Thanks to anyone who can help.