are they hard enough to cycle a tank
No, they were the last I added to my tank because they are not hardy, beautiful, but not good to cycle a tank with. I used White Sklirt Tetra's and it worked very well. Good luck!
From experience, my dwarf gourami's act a little weird even if the water parameters are SLIGHTLY off. If i don't have ammonia and nitrites at 0, it seems that they get a little irritated, so I would wait until you're tank is completely cycled and you have a good hold on your water quality before you add these beautiful fish. With patience, good things come
they arent good for cycling tanks but they are very good and very easy fish for already cycled tanks