We LOVED our STARband. I cried the night before our son had it put on because I was so worried about what people would say. He ended up having to wear 2 of them since he outgrew the 1st one (he had a painfully slow growing head and it took 10 months, not the original 4 forecasted). I would do it again in a heartbeat and wouldn't think twice about others' opinions. Your son could really benefit from it.
It wasn't just the flat spots, but some facial asymmetry as well (eyes and ears slightly misaligned, etc). He has some eye issues now that we believe may be a direct result of the facial asymmetry from when he was an infant, so I would ask about that too. It's usually more than just the flatness of the head, but that the most noticeable to the naked eye.
You can do so many cool things with stickers - I think that's why we know so many people in Jewel, CVS, etc since I always had his name on the front. You actually will see quite a few kids wearing them. Since Chase's helmet, I've talked 3 other moms thru this process and they, too, have been glad they did it.
Finally, the STARbands are terrific. He was in it for the full 23 hours within about 3 days. He slept with it and never really tried to take it off until he was older (about 17 months or so). Insurance covered both of them completely.
Good luck! It's a tough decision, but one I know we're glad we made!