Nope…but actually the one I weighed is a purple UV with the filter…can’t see that adding any weight vs stock, although the lens is a tad thicker maybe. I think mounting the light that way would be irritating (no adjustment) but sure. It could also encourage a split in a crash vs. breaking away or deflecting some of that impact. Back in the day before I plunked down money I hardly had for the early halogen lights, I taped two minimags to my helmet and attempted to have one on the bars…boy that sucked. lol. More exciting, though. 
I never used to think about “safety” like this, much less harp on it, but I’ve seen too much. Very odd things can happen in trail falls vs. typical pavement crashes, and you don’t even need to be going fast or on tough terrain. Very long time ago Bicycling magazine published a great tip-of-the-month: store your car key in your helmet using some velcro, and then it will never fall out of your shorts or jersey pocket. That was great, right, brilliant! Until that key becomes a harpoon into your noggin if you happen to crash and impact hard enough to crack the foam (doesn’t take much really, even with today’s better helmets). Along those lines, some of the “roadie style” helmets with rear projections that worked their way into the “mtb helmet” area pose some similar risks in off-pavement crashes and can accentuate head or neck injuries in the right circumstances.