What might make you want to ditch your self-hosted Mastodon instance?
With Lemmy, I didn’t feel a need to pick any specific instance because I can follow communities from anywhere, and it seems to work pretty well.
One downside I’ve encountered with my own Lemmy instance is that post and comment history in the communities I follow begins when I started following them on my new instance. New posts and comments are federated my way, going forward, but I don’t have the ability to go back and view as much history as one would on lemmy.world or lemmy.ml, for example.