from Mike at Rapid about clear vrs diffused lenses....
No, the other XM-L lenses we sell are diffused as well.
A clear lens doesn't mean it's better than a diffused lens, and vice versa. We've spoken to various manufacturers over the years about this and they all say it depends on the lens design. In most cases on narrow lenses (ie. 10, 15, 20 degrees, etc) you'll see a clear lens because the clear lenses tend to have more of a "hot spot" or "spotlight" effect. The diffused lens helps to smooth out the light so you'll get more even coverage. It's hard to describe but take a look at the attachment. The one on the left is a narrow angle (hence the smaller overall beam pattern), but look closely at the middle of the beam pattern. You'll notice a smaller circle within the larger beam. That's the "hot spot" that I was referring to. The picture on the right has a diffused lens and a wider angle, hence the larger beam pattern. However, you'll notice no noticeable inner circle within that beam pattern and a more or less uniform light.
I haven't seen Area 51's lights in person so I can't comment on their lenses. I suppose you'd have to ask them why they're using the lenses they are, but I can say for sure that having a clear lens doesn't necessarily mean it's better than a diffused lens and vice versa.