I have used on many types of fish, including Gouramis, Bettas, Platies...etc.
Personally, I have found clean water and a little salt (For fish that can handle it) do about the same thing as Melafix for healing fins. But I still think it's a good med for other things.
Torn fins is exactly the type of thing it's meant for. I find that pristine water is all you need for quick and perfect healing - even salt is not really necessary.
Melafix works wonders as long as you use tiny doses in smaller tanks (1/2 to 1/4 the dose). Make sure that there is plenty of aeration in the tank, and you gourami should be feeling better in no time!