instant on will get you before you have a chance to brake for sure, Cops around here pretty much exclusively roll with it on so far so I usually get lots of warning. Yesterdays was an instant on but he was parked with a chase car or two, must have been hitting the trigger pretty often as I had enough lead time to get slow. I was riding by myself but there was a few trucks and cars doing the same speed behind me, they must have seen my lights come on and slowed at the same time, one guy came up beside me gave me the thumbs up and mouthed , thanks man, LOL. we were doing 170km in a 100km zone, That light system I have is great for the daytime but your right, it lights the road up like the sun when its dark. Didnt know that Sena made an adapter but I bought one last year from china that works great, as long as I remember to keep a charge in it.