I don't have any personal experience but I have a friend who adopted two little girls from China. The little girls are so sweet and have brought so much love into their lives. But there has been problems. Emotional problems. Both little girls are seeing counselors. I think eventually their problems will go away since they are in such a loving home.
I think the younger they are the less problems you have. A baby would not have had as much trauma in thier lives.
God bless you and your journey with adoption. I wish you all the best.