I found that Dreamweaver often didn't take care of it - at least not completely. I can't remember the situations where changes were omitted, but it was certainly not a feature I could rely on; it was often necessary to fix some things manually. I can see it's not a simple matter - probably impossible to be 100% reliable and always to do what you intended.
George mentioned an exciting feature in relation to this. It would be interesting to know if this is on the horizon yet: