Upgrading to MySQL 5.6, benefits to switching to GTID replication?
I would say that you benefit from future proofing your environment, because inevitably you will want to add more slaves.

I also don't like having to remember specific coordinates of what statements have applied/haven't when doing a restore.  Having the server know the current set of applied statements is very useful to prevent duplicate processing/rogue corruption.  In 5.7 mysqlbinlog even has a --idempotent mode.

Operationally GTIDs are much easier to manage, and are the future :)

I recommend row-based replication as well - I think it's a great option:
http://www.tocker.ca/2013/09/04/row-based-replication.html