Thanks! My post as originally stated is wrong - the word "measure" has to be changed to detect if the GFCI CT saturates.
I'm glad you posted that - I had not even considered saturation, because all he wants to do is detect if there is any current. If gets any measurement at all, he knows the device is drawing current. I suppose I confused things by saying "measure" rather than detect.
Nice links, too. Here's another I like:
(Watch the line wrap)
Ed