When I provide a defaultValue prop to FormsyAutoComplete the value does not get rendered. I think this is because of line 82 in FormsyAutoComplete.jsx and I believe it would be fixed if value={this.state.value} is changed to searchText={this.state.value}.
This is with version 0.6.2, material-ui version 0.18.6 and used like this:
<FormsyAutoComplete name="example" floatingLabelText="How often do you?" dataSource={[ 'Never', 'Every Night', 'Weeknights' ]} defaultValue="Never" />