My only concern with projects like Odoo is that open source ERP seems to die off fairly regularly. How robust of a project do you think Odoo is? We'd like to be able to run it for a long while...
Check it out here: https://chart.ly/github-dashboard/odoo/odoo
From the Commits by Month chart, it appears that it has been active for about 12 years and it still fairly active.
Doesn't look like it is going to die anytime soon based on that data.
Also, I believe the cooperation that maintains the project also offers a paid enterprise version that offers mainly a more complete accounting module and handles the migration to any future versions.