Theoretically it's less sensitive, as IR film is the other side of the natural light spectrum from X-Rays. Therefore UV is closer than X-Ray than IR. However, AFAIK, IR film tends to be more light-sensitive than "normal" film, so it's probably about the same.
My advice is to get a string-net bag, put all of your films in it and smile. Say that you're a keen photographer and that you have previously had issues with film and X-Ray machines. Ask really nicely and politely if they wouldn't mind conducting their explosive swab test and their manual inspection rather than put it through the machine. You've got a reasonable chance of success if you don't encounter a peaked-cap type moron.
If you do find a security fascist, then there is nothing you can do - your films will have to go through the machine. It's in a theoretically good cause, so try and take it well. Gentle persuasion is the only option open to you and you'd be good to bear it in mind given "recent events". Getting a strop on in the airport is a guaranteed way to get the inside of your body inspected thoroughly!
R