I've had FiberGourmet Light Elbows and used it to make Thomas Keller's Macaroni au gratin. I could not tell the difference from the full carb version at all. According to the bag, it makes 4 servings with 23g carb per serving. I used half a bag and it made enough for 5+ servings for us. But, the cost is much higher than the regular macaroni for sure.
About 3 weeks ago, I tried The Only Bean - Organic Soy Bean Spaghetti pasta. Not sure if I overcooked but I did not like the texture at all. It was gummy tasting. Since I bought 3 bags, I intend to experiment to see about reduced cooking time.