I've yet to find the perfect running headlamp, but currently prefer the Zebralight 501. Previously, I was using a PT Eos modified with a Seoul LED.
The main advantage to the Zebralight is it's lack of mass. The beam is pure flood, but I appreciate the fact that it removes the tunnel vision you get with a tightly focused light. However, for me, it requires a handheld to go along with--something that can punch through the darkness farther. These days that usually a Nitecore D10, allowing me to standardize on AA cells.
I haven't tried it anywhere but on my head--seems to me it would move around too much. Perhaps it's be ok on a camelback strap, but I don't wear one of those.
For road running on good surfaces, I also sometimes use a Petzl E+Lite, which is really small. It's sufficient. It also has a useful flash mode, and a red led allowing you to mount two on one strap, with the forward one white, and the rear one red flashing. This is a pretty good setup, but certain not adequate for trails or broken pavement.
Jack