As far as I know all router fans vent air from top down past the bit. This makes sense in 2 ways. First, it helps keep dust and chips out of the motor. Second is that there is heat produced at the cut so pulling hot air from there doesn't make sense.
I have my dust collection behind the bit on top of the table and I get 95% or better for most operations. Many of the manufactured systems also collect from that spot.
Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.