The IP systems I've installed used a pretty expensive mux to send the images... I looked at what you were talking about on X10's website... sounds like a nice low dollar solution. I've used X10's products for about 15 years now and have never had a problem with them.
The only initial drawback I saw was that the cam had to be plugged into an outlet for electricity. I guess this shouldn't have been surprising, but it does tend to limit just how covert you can make the camera. Of course for an extra $19.99 you can buy a battery pack, which gets rid of the need for an outlet but limits your viewing time to four hours. Also, the camera isn't exactly waterproof, but it can be used outside if under reasonable shelter.