I never thought she had PTSD, only that she is (understandably) angry in general.
Plus PTSD is a hu-mon disorder, possibly not bajoran.
I've said many times before that I think Visitor is the Trek actor who improved most, technically, over the course of their series run.
To me, Visitor was very consistent. Her character loosened up because she had quite an arc, but her performance as an actress was spot-on from the start. I thought Farrell was most improved overall through the series, both her character and her acting. Avery Brooks also seemed to be more comfortable with his character once he was given the freedom he needed with his hair.
Probably the most consistent actor/character was Colm Meaney. His acting style reminded me a lot of DeForest Kelley. He also had the benefit of being an established character already, although I have a feeling he would have played O'Brien the same way even if he was a new character at the beginning of the series.