I don’t know about all the issues they claim to improve, but a friend has a 3rd level draft cross who developed anhydrosis and the patches got him sweating again.
Over the course of two summers she had tried every oral supplement on the market, beer in his feed, etc -pretty much every treatment she and her vet had ever heard of, none of which had any significant effect.
The patches worked very well for this horse. She’s planning do another course of them this spring to get him off on the right foot.
Her vet told her that in his experience they either work well or not at all for a particular horse. They ONLY were discussing non-sweaters, I have no knowledge of any other results.
ETA: This horse is/was already on electrolytes and always a very good drinker before using the patches.