My experience is anecdotal. Blue light supposedly washes out under moonlight if remaining unobserved is an issue. I have also been told a flashing or strobe effect with blue may induce an epileptic seisure. Doug's article is still timely on the subject. The Watkin's Aviation website lists a splendid unit with mutliple filters ( no assembly required!) much like a small maglight. I go for redundancy in lights ( and color) much like firestarting. The caveat ( especially for those with ageing eyes) to go slow at night, or if possible just stay put is wise advice, under any color 8O)