I opened a support ticket with Aeon and they said the nano dimmer is compatible with 3-way (and 4-way, 5-way, etc.), but there is a limitation to the length of wire in the circuit. Anything above a certain length (30ft) and the reliability of the nano detecting the switch decreases to about a 90% success rate. I think. Trying to get clarification...
If that's true, many of my 3-way circuits wouldn't work with this switch. I think anything less than 99.9% reliability is a no-go....