The sweep modifier yields very unpredictable results especially with acute corners.
It is lacking in many controls such as limits and segment controls. It also feels like it should have additional controls for aligning your sections as far too often it relies on sections oriented perfectly with reset xforms in order to work correctly.
The main issue is with 'overshoot' on acute corners where Max is lacking when compared to drafting software such as Vectorworks, Rhino3D and Autocad.
In the attached image, the top sweep is Max, the bottom is Rhino3D. Its impossible to achieve the same result as Rhino with the current sweep modifier.