Shaddows - 1:41 pm on Jul 30, 2010 (gmt 0)
De-duping has been fine for ages- certainly since it was in GWT, and possibly longer. I confess to never having de-duped a site, and have only analysed it since G started making a big deal of it.
Similarly, dropping the brandname from the title element has not caused problems for quite some time.
However, changing titles without changing content- particularly if you make incremental changes on the same page (as opposed to a single change from historic to final version)- that was positively dangerous