The settings are not stored in the servos, but it's more complicated than that. First, if the servos were shipped prior to December of 2009, they won't even work with the HDX without a firmware upgrade that must be done at Dynon. Second, although you can physically change connections between systems, that switching will not be simple or easy, and it introduces other problems. For one, servos are network devices using multiple wires, and disconnecting them from either system is likely going to produce continuous warning or error messages on that system. It's also possible you'd have to run the network setup again just to get them recognized. I'm sure there would be additional other effects or considerations that aren't occurring to me right now. Also keep in mind that by using two incompatible systems, you'll need to wire two completely different physical network architectures in your aircraft. Depending on your installation, that could affect more than just the autopilot. So, while it may be physically possible, and possibly workable, it would almost certainly open a can of worms you really don't want to deal with. It would be best to just choose one system to operate the autopilot, or use two compatible systems.
