the mesh will form a bit of a restriction, but that's its job as i understand. It is there to ensure that the airflow is evenly spread over the area of the AFM.
The hot wire element doesn't sense the airflow over the whole area of the AFM pipe so it reads it at the centre and i guess assumes this flow is even over the pipes area.
removing it may cause less of a restriction and give you maybe 1 - 2rwkw, but in the long run, i think you A/F ratio's will be less stable due to fluctuations in the AFM's ability to measure air coming into the engine.
make sense?