Kissing gouramy grow BIG, far bigger than lots of people anticipate.
They like algae and other vegetable matter, including your plants, though if you give them blanched spinach / lettuce / etc they may not bother with the plants so much.
I think other than that, they're fine in a community tank! I really like them, actually, but I think if the decision is between them and dwarf gouramy, you need to seriously consider the size they can get to.