I also use klonopin on an 'as needed' basis. The good thing about it is it lasts about 8 hours, but as long as you only take one dose per day or less, the likelihood of becoming hooked on them is slim (of course, I'm also on clonazepam, another benzo, for maintenance, so I'm already hooked, but since I don't get 'high' off of them, I'm okay with that and it makes my life so much better).
Today I will likely be taking my klonopin as I'm flying out on vacation and for some reason, airports give me the worst kinds of panic attacks. (not airplanes - airports).
As for IBS, it is very very common for IBS and anxiety to go hand in hand. Significant moderation of my diet has helped a lot with the IBS on a regular daily basis, but during a panic attack, nothing helps except drugs. I want to live as normal a life as I can, so I use the drugs.