While I might agree that catching someone else's swarm is generally a lot of
fun, I spend a lot of effort trying to keep my own hives from swarming.  A
swarm in my part of Maryland means that that hive is essentially shot as a
production colony for the year, as our nectar flow doesn't last long enough to
the colony to rebuild to reasonable strength during the nectar flow.  Also, I
keep colonies in a suburban back yard, and my neighbors do not appreciate a
pile of bees hanging from their porch lights.
 
My advice:  Consider a swarm out of one of your colonies to be a public
embarrasment, and work to avoid them.
 
W. G. Miller
Gaithersburg, MD