I have the Philips Lumiring tail light (battery operated version). It is very different from the design philosophy of tail lights sold in the US. You can look at it six inches from your face without blinding yourself. Yet it is very visible from a long distance at night. If you are used to a DiNotte or a Cygolite tail light you might be disappointed. There is no flash mode, no brightness levels. Just on and off. It is quite large (about 4 in wide), which I think is the key to visibility. I agree extremely bright and flashing tail lights are good for grabbing attention and that is what I use during dawn/daytime/dusk (Cygolite Hotshot 2W on the seatpost and L&M Urban 500 on the handlebar). However, IMHO, overly bright and flashing lights make it hard to estimate the the position, distance and speed of the bicycle in darkness. The Lumiring solves these problems. It behaves like a car tail light, not too bright, but yet very noticeable. Also, the Lumiring has a really big reflector in the center - almost as big as the light itself - which adds serious passive visibility. I realize that drivers in the US are conditioned to identify flashing lights with bicycles. So, in addition to the Lumiring on my seatpost I use a moderately powered red "blinkie" on the back of my helmet. This grabs attention and helps identify me as a bicyclist, while the Lumiring clearly locates me spatially. I'm sure not everybody will agree with my philosophy

BTW, I also have the battery operated Philips Saferide headlight. Its, the best headlight I've found so far for road biking. It goes to show the quality of the beam pattern is far more important than raw quantity (lumens). The only real downsides are the choice of power (come on Philips, NiMH batteries, really?!!!) and power management (the newer units switch from high to low mode after 70mins - I have an older version that runs for 2 hours on high). And, I wished it could be twice as bright. I like it so much that I had a second unit modded - the Philips Luxeon Rebels were replaced by a pair of CREE XM-Ls (!), new controller board and powered by an external Li Ion battery. I estimate the hot-rodded version is about 6 times brighter than the stock unit; beam pattern suffered a little bit, but not too much.

Finally, the broken mount problem was with the dynamo version and not the battery operated version.

In summary, IMHO, the Philips rear light (as is the front light) is excellent for night use.