When adding/editing a series there should be a release profile dropdown just as there are for quality and language, so that one can add realese profiles specific for a series without using tags.
Also the upgrade feature triggers only to upgrade quality, but it could also be triggered to upgrade release… h.265 releases are AT LEAST 50% smaller than h.264 ones (but take longer to be released). So download the first “quality profile” quality release (so you are up to date as quickly as possible) but when available, replace the file with an h.265 version (so your library is as small as possible). It would be extremely useful and important, specially considering radarr can quickly fill up any hard drive!