I'm not "afraid" of heights, but I do get slightly uncomfortable in high places, and I loved my one and only helicopter ride. I also don't like tight spaces (boy, I sound like a nut case, don't I?), so I think having all the glass, or whatever helipopter windows are made of, and being able to see all around me made it more comfortable than being cramped into a seat in a plane with only a tiny window. You'll be so captivated by the scenery that you'll forget that you're up high!
KB