The best way that I have found to test a UV treatment is to find a aniline leather swatch. Aniline leather fades more readily than anything I know. Run a strip of blue tape down the middle of the swatch, treat one side with the UV treatment and leave the other side alone. Place on the dashboard of your car's front window during sunny season. Leave it for a few weeks and remove the tape (longer if you do not live in a place like sunny Salt Lake City. You will see how much it has faded from the original and if there is much difference between the two sides. I have done this a few times on protector products in the past that claim to have UV protection. I have yet to see a noticeable difference between the untreated and treated side, even though both sides have significantly faded from the original protected by the blue tape.
However, I always remind myself that new innovations are being produced everyday, and just because it was so yesterday does not mean it is not so today. Also, the amount of UV absorber the manufacturer adds to the product matters just like in every other chemical product. Any one who offers up their product on a forum like this has done their homework unless they liked to get called out in public.