Hi Chris,
Yes, that's accurate. As of DSpace 8, we are able to build the backend (REST API) with Tomcat *embedded*. This was achieved via Spring Boot (which is the technology that the backend uses) in this PR:
https://github.com/DSpace/DSpace/pull/8797 Spring Boot has had this feature for some time, but we've only now figured out how to allow DSpace to utilize it.
At this point in time, this is a *brand new* option. It is still *one of two options* for installing the backend. You can choose whether to install Tomcat or not. There's not a specific recommended approach at this time.
We also do not yet know if it will be more efficient or conserve resources. It was added as a way to make the installation process easier, but we do not have anyone (that I'm aware of) who has tested this option in terms of efficiency, etc. In the future, we may make a stronger recommendation for which approach to use. But as of 8.0, we likely will just say "use whichever approach you feel is best for your scenario".
Tim