I recently upgraded Bitovi’s internal (but OS) Bitcentive app from CanJS 4.0 to CanJS 5.0. I added comments about the changes I made. Hopefully people find this useful:
https://github.com/donejs/bitcentive/pull/349/files
This is similar to the 3->4 upgrade post: Upgrading to 4.0? Here's a commented commit to learn from!