I use Fiber Choice, which is a different kind of fiber (inulin) than that in Benefiber. I think inulin is easier on the digestive tract. Also, I read somewhere that inulin is good for diabetics (but don't quote me on that!). Also, it comes in sugar free varieties.
There are also some double fiber breads that might help, but you still have to count the carbs.
Hope this helps.