I had the Cateye TL-LD1000- and was quite unhappy with it. It is so heavy that it is difficult to mount on anything soft- like a seat bag. (Can't aim corrrectly and goes flying off) So I put it on the holder on my rack that is made for lights, and it broke that off! I really needed it for a ride, so had it electric taped to the rack, and it was quite unreliable- turning itself off and on.
Right now I have two of these Cateye TL-LD600 Tail Lights-
http://tinyurl.com/oatyv - one on each seat stay, vertically, and another rectangular six-LED light that lives on the bike permanently. At night I use all three, plus a blinky on the back of my helmet.
It's pretty important to have the lights aimed correctly (horizontally) so they are easier for drivers to see- make sure they aren't pointed up or down.
A friend I ride with has a three LED light that is so bright it's impossible to ride behind her, almost. I am trying to find out what it is- I'll let you know.
Nanci
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"...I'm like the cycling version of the guy in Flowers for Algernon." Mike Magnuson