Yes, it is necessary to reinstall CKeditor (execute the propertiestool step) so the property is correctly added in portal_properties (with a default value of 'False' to keep existing behaviour)...  We could also, more or less avoid problems by doing cke_properties.getProperty('enableScaytOnStartup', False) but that would fail while going the the CKeditor control panel nevertheless...

So we sould add the instruction that collective.ckeditor has to be reinstalled, it would manage all this...

What do you think?