Just did a quick test, 1000 characters containing only a single sphere mesh all randomly moving around cost me 31-32ms. Without collision its 16-17ms, without the sphere mesh its 14-15ms. Without collision but with RVO avoidance instead its 19ms. So 200 should work, but AFAIK they cost the same whether they are on screen or not.
With a pawn and FloatingPawnMovement (again 1000 of them), with collision enabled and a single sphere mesh it costs 18ms, without collision 11-12ms. And without collision and without the sphere its 9ms.
And my cpu is an AMD 3900X.
So a pawn seems quite a bit cheaper. If you use FloatingPawnMovement with a pawn, then you need to have a capsule component as root component to use the build in AI movement (MoveTo).