Originally Posted by
hammond9705
I think you are missing the point. We are talking about a secondary light to put on the helmet. OP already has a good light on the handlebars and just wants a secondary on the helmet. Nobody expects to use it as a primary unless there is an emergency and the primary fails.
Even so, I would NOT use a Petzl headlamp or a Princetontec even as a backup. It's not worth it, when you can pay the same price and get a light that's equally convenient that packs 4x more light output and can clearly be used as a primary in case of emergency.