@noob111 not so much of a migration, but I wanted to start a new technology forum and choose not only a new domain, but also NodeBB in place of Flarum
This was a hugely beneficial decision. The SEO (actually, the entire platform) here is so much better, and the engagement is well over what I'd expect a relatively new forum to be in a short space of time.
However, as with all websites, SEO plus regular visitors, donations etc don't just "happen" - content is king as they say and if you or others post infrequently, then your content will become stale very quickly.