Hey @matttunney, when you’re opted into the new Design Manager, all of your templates and files are brought over and should word identical to how they did previously.
Modules created in the old design manager will be brought over as-is and will continue to work in content as they did previously, but will need to be upgraded to be edited in the new Design Manager. Once you opt to upgrade, you’ll be prompted to choose a host template type (page, blog, or email) where the module will be used. After the upgrade, you’ll need to republish the module, which will then update all instances of the module.
One thing to keep in mind here is there are some things that were permitted in the old module editor that will not pass validation in the new module editor. If that’s the case with a module you’re upgrading, we won’t allow you to publish and affect your existing modules until the errors have been resolved. (examples include: nested modules (modules inside of modules), include/import tags, raw hubl fields, etc.).