I wasn’t worried about it being proprietary until I saw the founder reasoning for not having the source be open under a nonpermissive licence.
https://obsidian.rocks/why-isnt-obsidian-open-source/
I decided to go with logseq because of it.
It also syncs with all my devices using my own servers, instead of needing to trust obsidian/logseq.
Yes, typically with two entirely separate disks, not just partitions on the same physical disk.