Good evening. Just got done importing 250 gb of US Census data into SQL. Ready to do some more data migration projects. It looks like you have mapped your data well. You did not specify if your database is SQL 2008 or SQL 2012, but it shouldn't matter. I have both platforms and can build your migration script for either. In addition, I regularly use SQL Server's SSIS tools, and would use this -- instead of Migration Assistant -- to build a customized import package that would loop through all available access databases. Deduplication, data quality, and reporting (rows in original table/rows in new table, etc) would all be included, of course.
I can begin as soon as you are ready for this project to start. Let me know.