no, really i dont, i only use GUI. but if something cant be done by GUI i always say, try using JASS, i dont know ANYTHING about JASS. GUI for the win ^^
JASS is all powerfull compaired to GUI but it is limated by the WC3 physics. To change the modle of how a unit looks with an item simply add a morph ability to the item that appon aqusation it uses the item transforming the unit into the other unit using ilidan morph or bear form. Simlar to that used in "P A R A S I T E - EX" for the suits. Appon dropping it will revert to its previous form.