Edit:: I have not made up my mind yet. Admittedly, at the time of posting I was leaning more toward that side.
After reading everyone's advice, I'm leaning more toward a multi-tiered approach as @jacquesm suggested. It seems to avoid bad karma and burning bridges. Also, it seems as though the PCI Industry rarely acts on reports. So, working with the competitor to fix their issues could be the best thing down the road. It's a very small industry, and the possibility of a buy-out could exist in a few years.