Ahh, You want to limit the angle of pathfinding behavior itself. I don't think it's possible to limit the angle of motion.
When path is generated Pathfinding creates a bunch of nodes on a grid and generally only moves along 8 directions - from one cell to another cell. [attachment=1:2xu10pot][/attachment:2xu10pot]
but actual movement of the object is more like interpolation between each nodes - object never perfectly lands on a cell where node is, instead it cut corners to move to the next node in shortest time. This is all done internally in the behavior.[attachment=0:2xu10pot][/attachment:2xu10pot]I've added Paster to draw perfect path of Pathfinding behavior movement along path..
Only way to sort this out I can think of is Ashley would need to add an option to the behavior so we could set how much this interpolation affects the movement. For example 0-1 based, where 0 is straight lines from node to node and 1 - this what we have on image above.
I can't think of any other solution - except of making your own pathfinder in events.