Ummmm....yes, I am very happy with my post.
Pretty much ANY DOT fluid is cross compatible EXCEPT DOT 5.
DOT 5 "will work", but it is even MORE water hungry than others. I do not believe it is a seal issue, it is water absorption issue. Thus, race cars is fine, other uses, sucks.

Now, mineral based fluids vs. DOT fluids is a different matter. Thus my question.

Oh, and to accentuate this, if you have an old system that uses DOT 1, using DOT 1-4 AND 5.1 is fine.

Yes, I made a bold statement, I will do my best to provide GOOD relevant links to prove, not just me stating it. Say, within 24hrs?