The main problem I have with auto-suggestions is that they distract my flow of thinking. Suddenly, I go from thinking about my code carefully, to reviewing someone else's code. To the point where I get a bit stressed typing, worrying that if I go too slow, the suggestion will pop up. As you may guess, I therefore have them turned off :)

I am playing with Zed now though, and it has a "subtle" mode for suggestions which is great. When I explicitly want to see them, I press option key. Otherwise, I don't see them.