I would argue that much of IBS is driven by bacterial overgrowth and that the SCD Diet is extremely effective and rebooting gut flora and starving out bad bacteria to alleviate the symptoms of IBS.
I have been on the diet almost 2 years and I feel amazing. It's worth a shot, what's the worst that could happend, it doesn't work? Try it for 15 days and see how it goes. Just make sure you start it properly with the intro diet, that is crucial for bacterial overgrowth.
If it helps anyone, there's a free guide on how to start the SCD Diet in 24 Hours and survive the intro diet over at http://www.scdlifestylebook.com/free.php
if you are interested.