If it works for VIs generally, then you should keep the same policy for methods of the class. Classes are just a system for organizing the VIs you'd write anyway. And being reentrant does mean all overrides have to be reentrant, but that shouldn't be a problem. For one thing, method overrides are generally adjustments to the parent's behavior, so if the parent didn't need synchronization, neither will the override. And if it really needs synchronization, the override can call a subVI.