With overlay you're entirely at the mercy of the GPU, which is usually a horrible idea, even EVR does a better job then that. Also, Overlay has some other issues, window movement is sluggish and it forces Aero off. Its the most efficient renderer in regards to performance (if you dont want DXVA), but its also the most simple with basically zero features and zero control about what happens. That it turns Aero off is already annoying enough for me.
From a technical standpoint, its also brain-dead stupid and doesn't implement DirectShow properly, so right now its broken again with LAV and probably needs some custom hacks to work again.