I also am working on a project to update a bunch of outdated resource groups. For us, the main problem is that we have to change both the active jobs, and the underlying master part. I created a series of BAQs and customized dashboards to help with this exact thing.
Check out these two posts for an overload of information:
Of course, the pros will tell you to buy the DMT and do it the safe way.
Good luck!
Nate