Hey Robert, you've probably read on this site the opinions regarding fuel management sytems that "piggyback" the ECM (PC III, DFO) and those that replace it (SERT). I have a great deal of confidence in the opinions giving by our brothers and sisters here, as they are backed by experience in the field. The big picture I've walked away with here, and one that I agree with 100%, is that you need to use the devices that your dyno tuner suggests. Of course it is a given that your Dyno man is indeed "The Man".
My personal experience with a DFO wasn't good, but there are plenty of guys that have used them with great success. I ran a DFO on an '05 FLTRI which had a SE Stage I airbox, true duals, and Wild Pigs. The bike ran pretty well and I was very satisfied. However, on the way back to Ohio from Sturgis that year, my DFO apparently failed and since it was a "piggyback", my ECM returned to stock settings which were quite lean. It fortunately didn't damage the motor, but keep in mind that when you're hammering the throttle on a return trip home, your ECM doesn't exactly send you an e-mail to let you know there's a problem.
Consequently, I sleep better at night as my '03 SERK has a race tuner installed and it gives me a little bit of piece of mind. Just my experience.
Ride Safe,
Joe