Moodle upgrade headaches version 2.4.9 - 2.5.5

I have spent the better part of today trying to create a test instance of a moodle instance that we are planning to upgrade from 2.3 to 2.6.

I have go through this process 3 full times now, with very little variation in my steps and keep getting the same result.

When I am at the plugins check, trying to update the DB from version 2.4.9 - 2.5.5 (each of these is the tip versions of the well, versions).  I am greeted by a very disheartening DB failure.  This is what is says:

I found this forum post, so I know I am not the only one who has experienced this. I tried a solution similar to the one noted in the article - deleting the table manually from the DB, I even tried deleting all 5, which did allow this version 2.5.5 to complete, but then when I upgraded to 2.6.2, I got this message (related? not sure).

Cannot downgrade repository_alfresco from 2014020301 to 2013110500.

I'm not sure if its related to me manually deleting tables out of the DB.  This seems very stupid and clearly, I am losing any data that may be in the tables. 

This is the first real headache I have experienced doing a standard moodle upgrade.

One silver lining is that I have become very profiecent at the windows command line issuing my DB restore commands.  I have been into my SQL program issuing restore orders about 5 times today.  Each time I have a failure, I restore the DB to its 2.3 state and then proceed, again, with the initial upgrade to 2.3.11.

This is my process

1. restore the DB with todays DB backup, made using moodle 2.3.x
2. update the code base to 2.3.11 (2.3 tip)
3. browse site - DB updates - log into instance.  good
4. update the code base to 2.4.9 (2.4 tip)
5. browse site - DB updates - log into instance.  good
6. update the code base to 2.5.5 (2.5 tip)
7. browse site - DB updates ...... and BOOM, fail

More to follow...