Yeah, it would have been nice if they had gotten some other kind of ship. The Defiant went out in pretty spectacular fashion and it was a shocking turn of events. Then they turn around and replace it with the same exact ship.
19-year-old me wrote a rather fanboyish alternate version of WYLB in which the new ship was an evolved/perfected version of the Defiant class named Saratoga and Sisko made a rear admiral. I even started on a season 8, with the core characters Kira/Ezri/Bashir/Nog and Benteen from Paradise Lost as the full-time captain of the Defiant.