Actually had two aircraft with them on the tail. The difference I noticed was a little better authority of the elevator and rudder and slower speeds. It wasn't a lot but it is enough that helps for those real short strips that require minimal speed on landing. I fly out of my own strip in north central Mn and originally it was less than 1,000' with very tall trees on each end. Of course the way my strip is oriented i have a crosswind most of the time sogetting down and landed in the shortest/quickest time was neccessary.

In regards to Skypirates question, they are normally installed at 10-14% chord. I have read of guys placing them closer to the leading edge and getting good results but a simple google search will result in enough info to digest for many days!!