Pros : Really makes those folds with a solid base. I found that even small feet under it allowed enough airflow as it's hollow. Tends to leave some shine on the inside.
Cons : difficult to melt all the way to the bottom- your pieces will not be as large as the mold without stilts under it.
Other Thoughts : Use lots of kiln wash. Varying the temp of your slump radically changes how it drapes. I find that a total plus!