I've used Irish Moss in about half of my beers, some of them extract some AG. I can honestly say that they are all about equally clear.
Following Palmer's advice and not using it would be the safe thing to do and your beer will probably be just as clear as it would have been otherwise.
Kegged: #114 Oatmeal Stout, #115 American Amber
Planned: APA, IPA, Nut Brown