I just finished a summer-long DS9 re-watch tonight; the first time I've seen the series since it aired. I dreaded the Jadzia-Ezri changeover. Terry Farrell, you see, managed to hit almost all of my "she's hot" buttons back in those days, and Ezri was good, but only "cute" in comparison.
But this time, I enjoyed Ezri a lot more. She seemed played by a more competent actor than Jadzia, and it was fun to watch the Trill dynamics of a new face with the old memories work their way through all the characters over several episodes. As Greg Cox points out, it's a lot like the Doctor regenerating, you can't simply ignore it. And DS9 focused a lot on the characters. If they'd brought in another Dax and didn't show how the established characters integrated her back into their relationships, it would have been a huge cheat.
About halfway through the final season's fourth episode, it suddenly occurred to me that Ezri should have been a man. It isn't just rebirth in a new host that makes the Trill symbionts interesting, they can also change sex. This was explored a bit in the Next Gen episode, "The Host", and Dr. Crusher wasn't able to keep up with it.
I'd go even further. If we're gonna explore this, let's drop all pretence of metaphor and just make the Ezri host homosexual. Or at least open to the feelings he recently had for Worf and/or Julian. In the 90s, homosexuality was still a bit taboo, and contrasting this with the Trill taboo of continuing the relationships of the previous host would be neat. Watching Worf and Julian react to that
would have been fascinating. He wouldn't have to be over-the-top. Perhaps he wouldn't even have to be overtly homosexual. But he'd still have to resolve his feelings for Worf.
It's interesting that the talented crew behind DS9 missed this opportunity. Especially given the hints at lesbian relationships in several episodes. I'm sure this must have occurred to someone, but I wonder why they shot it down.