Interesting.. beginner triathletes tend to use them
At the tri shop in Orem, Utah where I have worked, the beginner triathletes would come in for the jammer bars. When using a road bike, you are probably not going to get into a really, really good aero position. However, the jammer is just like when you put your forearms on the handlebars in an aero tuck. They work for nearly everyone who bought them. In over a year of working at the shop, I have never had anyone say anything bad about these bars. They are comfortable for the position you can achieve.