I haven't tried the IAL yet. I was considering dropping some blackwater extract into my fish's QT tank until my leaves get here in the mail. My other fish sheems to LOVE it, though. No, I'm not sure what could stop it. My male was doing it, but since I've moved him to a smaller tank he hasn't had that issue. Maybe he just doesn't like large tanks. Not sure. He did it the first time in his Qt, though.
Stress coat has helped me fish adjust. I've made it a rule of thumb to just add it in when acclimating a new/stressed out/sick fish.
I've never used vitachem, so I can't really give any advice on that. :P