When you initially create a drainage area from a shape, it creates 'smart' vertices that you can grab and move with the cursor. However, after the initial catchment shape is created, the only way to add additional vertices is using the "Insert Vertex" command, which adds 'dumb' vertices to the catchment area. The issue is that if you then move one of the initial 'smart' vertices, all of the 'dumb' vertices that you added after the initial creation of the catchment area then get deleted and it resets the shape back to just the original points it was created with. The highway jobs I work on have constantly changing designs, so trying to update these catchment areas after they were already created based on a previous design is very time consuming compared to Geopak where I could simply add and remove any of the vertices as needed.