1.9.4-rc2 introduced some calls to LOWER() in Metrics.pm that don't work with SQL Server as LOWER() works only on varchar or data types that implicitly convert to varchar. See:
topichistory.reviewers and topichistory.cc are of type ntext(16) so require explicit casting.
In sub _get_topic_history_rows() this seems to work for me:
'LOWER(CAST(topichistory.reviewers AS varchar(16))), ' .
'LOWER(CAST(topichistory.cc AS varchar(16))), ' .
but I'm not very familiar with this stuff so I can't be sure this is right.
Also there are many other new LOWER() calls in this version of Metrics.pm that I haven't checked - I've just hacked a workaround for the problem I found.