modern gasoline engines are designed around low-solvent, low sulphur gasoline, which, in it's very own self, is a very unique blend that unlike gasoline sold a couple of decades ago.
I don't believe (nor have I seen any for autombiles I serviced over the past 20+yrs) any benefits of UCL. Good fuel injector cleaners, on the other hand, will keep your fuel injectors in good spray pattern and gum/carbon free, which will greatly extend the life and longevity of both your injectors and your engine (less fuel dilution in oil means less wear on your cylinder walls, etc.)
Q.