I think, using your
own examples, is that the symbiont has the same amount of control over what happens to it as the host does. Our natural instinct is to preserve our lives. Dax hosts just 'go for it', regardless of the potential consequences to the host. It has done this 8 times and is still alive. Us humanoids only get to **** that up once.
One has to assume that there are degrees of control here. How tight you hold the reins, to use the idiom. In my opinion, Dax could have prevented Joran from ending people's lives, if it wasn't so interested in that aspect of humanity. That puts the influence of humanoid morality into serious question.
My observation is that Dax doesn't share our sense of morality, just sees it as a learning opportunity despite the cost, and I wouldn't trust it half as far as I could throw it.
Also, Average, although we disagree on some points, I appreciate your willingness to discuss the point. I really wanted to earlier today and it bugged the hell out of me all night at work that I couldn't.