Caught a brief preview today at the Theological Research Seminar of Elaine Bernius' dissertation on the dialects of Job. What fascinating and painstaking work! She considers concentrations of words in various categories like Israelean, "foreign," Late Biblical Hebrew, and Standard Biblical Hebrew, while also considering of course extra-biblical sources like Dead Sea Hebrew and Mishnaic Hebrew.
In general, she believes the dialectical elements of Job's comforters may be a stylistic feature, a deliberate projection of foreignness on them, pointing especially toward the east. Aramaic words would then not be particular evidence for lateness but more a stylistic element. Perhaps it is no surprise, then, that her adviser would be delighted if God turned out to speak Standard Biblical Hebrew. :-)