Yes I think it makes sense to start with 7.0.0-rc.1. But I'm new to Unraid and I wondered about some other potential issues compared to 6.12:
I have installed a 250GB SSD which I intend to use as a download cache to try to make the most of my 1Gbit fibre connection. Am I right in thinking that a full ZFS setup would not be able to use that, as it only caches in RAM? Then again I think the cache is not on the filesystem level and relies on a scheduled task to move data from the cache to the array? I'm probably not going to have a parity disk for the array or the cache as I won't be storing important data initially. I may add one later.
Could there be compatibility issues with some community apps on 7? I intend to run Jellyfin, but as these are just Docker containers I don't expect any issues. I assume there is a bump in the Docker engine version but I've not been able to find the details on that in the release notes.