I don't normally need lights to see by, only to be seen, so I use a 1W PB Blaze in flashing mode. One bright, sunny day an oncoming cyclist asked me to stop. Upon stopping he informed me that he was an epileptic and that my flashing light could cause him to have a seizure. After a long deliberation (and posting a new thread about the incident here) I decided that my safety more important to me and my family than the risk that my light might pose to any unfortunate oncoming epileptics. After all, the emergency vehicles around here use strobe lights to catch the attention of oncoming traffic, so why shouldn't I?