60mm fan is primarily for the good old days when CPU's aren't very hot and a 60mm can do their job. Also, some mobo don't have nice clearing around the CPU to allow you to use a 80MMHSF combo. Generally case fans should be 80mm or bigger.
If you want to suck air out, but it in the back. However, 60mm stealth probably won't generate any appreciable difference since it's output is so low. Probable under 10CFM.