Basically I will be riding 21 miles of mostly unlit roads at 8-9PM and am not sure if I really need 700 lumens. I don't plan on doing any trail riding at night yet so I don't want to buy a light based on something there is an outside chance I would do in the future. I plan on having a small 100 or less lumen light on my helmet more to be seen then to see. would I be just as well served by a Seca 400? I don't want to just get the best because that's what I typically do and sometimes I regret it. This will be for a cyclocross bike that I will be using as a commuter.