Regarding Odo and the bat’leth-wielding Klingon coming up behind him: I recall several occasions in which small pieces of a shapeshifter were removed from the main body mass, and then rejoined it. But was there ever an occasion in which a shapeshifter was separated clean in half? A quick slice of a bat’leth from behind an unprepared Odo would have accomplished that. Do we know for sure that a shapeshifter could recover from that? More to the point, do Odo and Bashir know for sure that Odo could recover from that? I hope I’m not violating the TrekBBS standards of conduct. I know that bumping old threads is discouraged, but I don’t know how old is old. This thread has been idle for a few hours shy of one month.
TrekBBS is pretty laid back about resurrecting old threads so long as you continue the discussion, as you've done. We really don't know anything about his physical make-up. My guess would be that his body could reconstitute itself after just about any level of fragmentation, so long as he isn't damaged on a cellular structure.
I've been rewatching myself... there was a scene in the first season where Odo, faced with an airlock barring his entry onto a ship, melts down into liquid and gets through the airlock somehow. Some airlock!
That head knock out with debris really bothered me, too. I do understand that the writers didn't want Odo to be indestructible, but having him KO'd by a blow to the head seemed very contrived to me. I also agree that if he had lost consciousness, he should have dissolved into a puddle of goo, not remained solid. On an unrelated note, I was very glad that in that episode, they decided to send the kid and her father to live with the Vulcans. The thought of Odo having some alien kid tagging along after him and keeping him from being too lonely made me gag. It would've been the equivalent of the baby effect on so many previously successful shows that die agonizing deaths after some nimrod decides a cute kid will boost ratings. EDIT: That airlock business bothered me, too. If Odo could get through it, you'd think that air could, too!