You do not count either as a carb. Soluble fiber is absorbed by the body, it lowers cholesterol, and will lower the GI of a meal.
As Dr. Lowery said:
There's growing evidence that higher fiber intakes offer lower risk of fat gain, partly by lowering the insulin and glycemic effects of a meal. About 5g of soluble fiber can drop the glycemic index of a sucrose meal by 50%. In fact, in a 50g carbohydrate portion, each gram of beta glucan predictably lowers the G.I. by 4 units. That great, at least for non-workout times of the day. Men should get 38g of fiber per day and women about 25g.
I have not heard anything about too much fiber, but you can look at this site for more info: www.healthcastle.com/fiber-solubleinsoluble.shtml