I am working on a firmware upgrade to the XTB-ANR to operate in a "stealth" mode. Rather than always attenuating everything on the powerline, it monitors the background noise level, and only switches on its attenuation when the noise level rises to the point where it could begin to affect X10 operation. An added feature pulses the LED briefly every two seconds to give a crude monitor of the background noise level.
The reason for the upgrade is that I had been working with someone dealing with some serious signal suckers. He thought the problem was due to noise, and had added XTB-ANRs to his system. XTBM readings showed absolutely zero noise and very weak signal levels. The signal from one remote transmitter was too low for XTB-ANR to recognize to turn off the attenuation. We eventually isolated the worst signal suckers, and signal levels came up an order of magnitude. So did the noise levels, and now the XTB-ANRs are actually doing something.
A few beta units are available for evaluation. Please contact me directly if you are interested.