I've a pretty basic torpedo7 one, think it is about 100-120 lumen. You will want something relatively light weight otherwise it'll bounce around when running. Mine has a strap that goes around my head and that works fine for me, but some people find having the additional strap over the head stops it slipping down. if you are trying them out have a bounce around and see how secure it feels as you wont want it falling off partway through a decent and if it needs to be really tight to stay in place you just get a headache.

hoping to start at 7:30, so it will probably still be fading light/dusk still but by 9 when we are finishing the it will be night.