good morning Val
and congratulations again on your on going project with the 55g tank.
I have also heard that exact same thing. The sailfin mollies or molly in general can live without the salt in the water, and it is used basically when you want to breed them. The Krib that you have also uses some saline in the water as well. But I am not sure about your dwarf gourami, whether or not they would tolerate the saline conditions. So I would be careful of that.
Good luck with your fish and dont forget to post photos asap!!

~ kate