I have a 235 lumen LED light I got from Gander Mountain for like $35 (just looked it up, seems the price went up). One of the best purchases from them I ever made (had a gift card, made it even better). My only complaint is that the switch is on the side, not the back. When I first got it I also made the mistake of shining it in my eyes. Not only the blind spot but I had a huge headache the rest of the day. I can't imagine what 700 lumens would be like. Mine also takes CR123s.
I think when someone says that a 60 lumen light will blind an attacker, they may be referring to an attack at night or in the dark. It won't take much to activate all the rods and cones in a person's retina and cause that "flashbang" effect if their pupil is wide open gathering all the light it can. The much brighter lights, like ours, create such a huge blast of light that it could temporarily stun the attacker if they are looking directly into it. Even if they aren't looking into it, they can't look at it at all, giving you an advantage. I carry mine to school because I can't carry my firearm on campus