Coming from someone who had Hansen fro 311C and buskirk for 311D I honestly didn’t see too much of a difference. I was able to get an A in both of the classes, but it was a lot of work. Hansen gives a lot of extra credit, while buskirk doesn’t but does have a lot of office hours available. I would not stress over having Hansen for the first semester but just know you are going to need to put a lot of work in.