There are two things that I don't like about front porting. One is the possibility of port noise when playing them hard. This is not a factor with the A/V-3 though as it has a large opening for the transmission line.
Next is that you get what you get. In other words less flexibility. With the port in the rear you can vary the distance to the back wall and vary the gain from the port a little bit. When it is in the front you don't have this flexibility.
In the sub 200Hz range the power handling of the A/V-3 and the OB-5 are the same.
