Maybe have Worf and Sisko piloting the Defiant, where Sisko in some regards is Picard's voice of reason regarding the Borg so to speak.
Practically, you're adding an extra salary and reducing other actors' lines for no bigger/better result.
Contractually, Michael Dorn was guaranteed that signing a contract with DS9 would not preclude him from doing TNG movies. Conversely, Avery Brooks was resistant to doing stuff beyond the actual TV series - still rarely does conventions and refused to participate in the "Making of DS9" video that came out after Season Two, or even grant permission for his image to be used in it. Colm Meaney had became a bigger-ticket movie star (beyond his TV contract), so he would have been expensive to use in "First Contact", too.