I have the smoked tail light on mine but with an LED bulb. They aren't as visible as a red tail light so as far as safety goes they definately aren't as safe. They are bright at night though. They look awesome though and I'm happy with mine.
I've got the Kuryakyn Panacea lay down smoked lens with matching turn signals front and rear. I think it's a great system, when you hit the brakes all three lights in the rear flash red then stay solid red, when you hit the turn signal the signal and half the brake light flashes amber. Really hi-viz at night a little less bright then stock in direct sunlight. Expensive though, not for the timid.