I look at hard surfaces as an opportunity to concentrate
water that can be captured.
In both the spring and fall, I have many freeze-thaw cycles on a daily basis. I seriously doubt that a porous
concrete would last very long in my situation. Frost is a very powerful thing and would probably blow it apart in a few seasons, the same as it does with porous bricks.
Tree
root heaving, is always a problem around here. One thing that can reduce this is having a very dry environment under pavement. The porous material allows for aeration and water infiltration. Both of these properties would tend to encourage tree
roots to develop under the material.