I want to be clear that I'm talking about the Arby's classic (the smallest of the three RB sandwiches). The middle one has about 1,550 mg so it is higher, but comparable to a CFA sandwich. Still, chicken is supposed to be a healthier alternative to red meat.
Another comparison is that a Kentucky Fried Chicken Original Recipe breast has 1,190 mg to the CFA's 1,400 mg. The KFC recipe (which I've figured out) is basically salt and pepper with some herbs and spices (salt, celery salt, garlic salt, black pepper, white pepper, paprika, thyme, basil, oregano, ground mustard, and ground ginger).