I absolutely swear by my aero bars on my trek roadie. I have heard of some here mounting them on bikes with straight bars.
It is by far, quicker and cheaper than fussing around with changing out handlebars. They bolt on in minutes.
Your LBS might have a set kicking around that they'll let you borrow to see how it works.
One word of caution. Have plenty of room on both sides, the first time you drop into them. I damn near killed myself almost going over a guard rail on a long fast downhill, the first time I attempted to get into them. Now, I can do it in my sleep.