I have an H&S tuner on my 09 Superduty. It has been on there for over 3 years. The truck has a lot more power. Pulling the 5th wheel is much more enjoyable. My truck doesn't feel to be working as hard as before the tune. I baby my truck and my fuel mileage has increased by 20-25%. The cost of the tune and associated mods was about $2k which I recovered in less than 2 years operating. I have had zero problems or issues with the truck. And for what it's worth, a Ford dealer did ALL the work on my truck including the tuner and associated modifications (while my truck was still under warranty). I can't speak for anyone else, but my experience has been nothing short of excellent.
Would I do it again? I hope I don't have too. My plan is to keep this truck forever. However, with the constant changing environmental regulations, the option could be gone in the future anyway.
Just my thoughts.