I had created a project that defined some content types and lists via XML. After it's release we need to make some updates to this feature to include some new functionality. My concern is that since this was all done via XML major issues could occur.
The lists initially created are critical. By doing an upgrade-spsolution is it going to tear down the lists and try to provision new ones or will it see they already exist and do nothing? The updates aren't touching the lists themselves, but updating some ASPX pages, javascript files, and adding in localization.
Since this project, I've moved to creating and provisioning lists via feature activation code instead of static list instances, I could handle it all in the feature upgrading event receiver if that were the case.