I actually agree with the majority, for the most part in Dred Scott. Not from a moral aspect, of course, but from a legal aspect. The dissent's argument just doesn't make sense, and it's absurd to think that a country could allow people to be citizens in one state but not another.
I do agree with the dissent when it comes to analyzing the militia law, and I think the majority's argument there is weak and severely logically flawed, but it's not necessary to their overall argument.
The interesting part of the case is what could've happened had it been held the other way. If that had happened, it's very possible that the Civil War would've started earlier, when the North was not yet strong enough to have one.
In my opinion, it's a legally sound holding based on an interpretation of a racist document written by a group mainly made up of racists (or those too weak to challenge the racist aspects of it).
Too many people work their way backwards on the case, knowing as we know today that it's a morally abominable holding, but that doesn't mean it's a legally "wrong" holding.
I have to differ with you here, regarding the majority opinion's legal logic. Since Taney concluded that the case lacked diversity jurisdiction because Missouri courts had already concluded he was a slave and not a citizen, there is absolutely no sound justification for the remainder of the opinion. How could the Court possibly determine that blacks couldn't be citizens and that the Missouri Compromise was unconstitutional while simultaneously concluding that they didn't have a basis for hearing the case in the first place?