Wayne,
"Just staying quiet" may work or it may not. For some flying sites, in my opinion it is not smart.
One of our fields is adjacent to a smaller towered airport. A group of our fliers reported that the tower supervisor either heard our guys were flying, or saw them. He immediately came over to the grassy field we were renting. His initial suspicion was that we were flying drones, and he was going to shut it down. He was apparently patient enough to listen to an explanation of what control line was, and how the plane was tethered and then strapped to the wrist. At that point, he told us to have fun, and went back to the tower. It could have turned out very different.
What we need is an FAA memo to the field offices that provides guidance that control line airplanes are tethered, that they are not remotely piloted (no RF link), that they have no GPS coupled autopilot and cannot operate autonomously, and are not within the category of sUAS by both the FAA and the Congress' definitions. With such a guidance document in hand, we could refer to it when parks people try to shut us down for operating in a VIP TFR area, for when we are within a 5 mile radius of a tower without a letter agreement with the tower to permit sUAS flight, and for when they simply call the local police to enforce a "no sUAS" policy. It would also exempt us from the FAA registration and marking requirements. Using a memo to provide a rules interpretation--a guidance document--is how the FAA normally operates.
I made an attempt to get the responsible AMA person to do this (relative to the VIP TFRs) back in April of 2011. I was rebuffed. The reason given was that we (control line guys) should not "rock the boat." And here we are. Still. The situation has not "gone away by ignoring it." It has cascaded into the sUAS thing. If we had dealt with the control line exception back then, it is highly likely that it would have carried over into the rules being rolled out today.
So everyone gets to make a personal decision about whether to register, mark, or even fly. If you fly in a city, or near an airport then getting that decision right becomes important. If the tower calls the local cops and they come out and confiscate your equipment, do you think the AMA would have any ability/interest to intervene on your behalf? That would be rocking the boat....
In a way, it is kind of like making an omelet. If you are doing everything you can to keep the fragile shell from breaking, you aren't ever going to accomplish anything.
Dave Hull