The advantage of smooth trimming is that the boundary of the part will follow the trimming curve exactly. However, it will result in some very bad aspect ratio when the boundary elements are cut. And these bad elements will cause trouble for the later springback analysis.
The advantage of non-smooth trimming is that it will not affect the aspect ratio of the element, and it will not cause extra trouble for the later springback analysis. However, this boundary geometry from this method usually cannot follow the trimming curve. Even though the boundary of the part is not good, it is seen that the spring back prediction is not affected obviously.
For most of the simulation, it is recommended the non-smooth trimming be used.