But excluding itself, tungsten cannot be perfectly compared to any other element, alloy, substance, or known material( in that way), so why should we believe that it could magically compare with durasteel as a ratio of this much to this much when it cannot compare with anything else in such a definite way.
That is not to say that the armors could not be compared. If you were only comparing strengths, boiling points and the like, then they could be compared, but taken as a whole, there are still to many variables to consider.