Hahaha that's a different question than your original one. Seemed like you were contemplating whether or not to present a series of silhouette photographs, and asking for pros and cons
hmmm, off the top of my head:
1) appreciable difference in exposure level between background (brighter) and foreground (darker)
2) simple, non-distracting background
3) clearly-defined subject (distinct outline) to form a silhouette with.
4) be careful of any distracting elements.
Sounds as we are asked again to do somebody else homework..?
TS: If you want to do silhouettes just for the sake of it then do it on your own as technical exercise. Not too difficult to go out at sunrise / sunset time and do trial and error till the shutter smokes. But (looking at the quote in 2nd post) if you decide suddenly to use this style element for a certain assignment then it's a bit too late to ask now, 5 minutes before the job starts. There must be a reason for you to select this style. So, best is that YOU evaluate why and how this style can help for the assignment. If you can find good answers - go ahead. If not, well .. wrong choice then.