Your problem is caused by the change from an ID of #suckerfishnav to #suckerfishnav3.
The Javascript used to trigger the :hover pseudo class in IE6 is specified for an exact ID, the plugin is set for #suckerfishnav, so when you changed to #suckerfishnav3 it prevented the dropdowns from showing.
You either need to change your ID’s back to #suckerfishnav or hack the suckerfish_ie.js file.