I would agree and be on the safe side. Have all your film together in a clear ziploc bag in your carry-on, ask (politely) to have it hand inspected. There's three different ways I've had mine inspected:
- guy takes a quick look at them, says they're fine (least often)
- guy runs a swab over all of them, does a chemical scan on the swab (most often)
- guy picks a random sampling (1 in 5 roughly) does a thorough visual inspection, takes them out of the cardboard box (if they're still packaged) does a separate chemical swab for each (slightly more often than a quick visual, takes FOREVER)
To be safe, budget an extra 20 minutes to get through security if you're getting film hand inspected, I've only ever had it take that long once or twice, but better safe than sorry, it usually takes about 5-10 minutes depending on how busy they are (some airports, the security manager has to do all hand inspections, some will let any security officer do them)
Technically ISO 100-400 shouldn't be affected AT FIRST... the effect is cumulative though, so if you're going through scanners multiple times during one trip, or the film might last through a couple trips it'll add up. As long as you're polite and have it all ready for them, it shouldn't be a problem, they get testy if you're fishing around for stray rolls. And if they try to tell you "oh, it should be fine, you don't need to", just tell them you travel alot and it could be going through a lot of check points.