Any instance, large or small, is only as good as the admin team running it. Ultimately, the larger instances have more content on their all feeds, are generally more stable, and are less likely to suddenly disappear. Smaller instances are generally faster, have more direct contact with their admins, and have more user control. Ultimately if you are having a good experience on lemmy.world you don’t have a strong impetus to switch, but I would maintain alt accounts with your subscriptions just in case. You can use a tool called lasim to port them from one account to another. Though I am biased, if you do decide to move to a smaller instance, I have a brand new one called lemmy.thesanewriter.com that I am currently the sole admin of that is accepting new users.