I finally took some time to record what the XTB-ANR can do to powerline noise. Below are a series of photos showing how the XTB-ANR deals with the noise produced by the Lumoform LED light that is the worst powerline noise generator I have encountered.
The first photo shows the raw powerline signal measured through an X10 Pro XPCP passive coupler. You can see the noise peaks at almost 2Vpp. Zero crossings of the AC waveform are at the two points on the left and right of the trace where the noise level drops to zero.
The second photo shows an X10 signal being added to the powerline. You can see it begins just after the left zero crossing. The variation in amplitude is due to the noise and the X10 signal summing together. There is virtually no way an X10 device even with AGC could extract that signal.
The third photo shows the noise level after the XTB-ANR plugged into the powerline. While it can reduce typical powerline noise by about a factor of ten, it only does about a factor of five in this example due to strength of the noise source and the relatively little powerline inductance between the noise source and the XTB-ANR.
The forth photo shows an X10 signal again added to the powerline. You can see that the first portion of the X10 signal burst is attenuated until the XTB-ANR recognizes the valid X10 signal. At that point it switches off the attenuation, allowing the full X10 signal to come through. As in the second photo, the variation in amplitude is do to the noise and the X10 signal summing together.
On the right side of this trace you can see the faint shadow of a prior X10 burst due to the persistence of the scope CRT. The difference between a logic "0" (no signal burst) and a logic "1" (with the burst) is about a factor of ten. An X10 module incorporating AGC should have no trouble detecting this signal. It might be marginal for a standard X10 module if the noise frequency is near the X10 120KHz passband. But remember, this is the worst noise source I have found. Noise from a more typical noise source is reduced even more.