Tail light effectiveness is a tricky thing. I myself have a Cygolite Hotshot, which I think is plenty bright even for daylight use, but it's a narrow focus type and aren't as bright from the sides (even though I can still see it beyond 90 degrees). In fact, I saw someone who modded their Hotshot with a wider angle lens to try to compensate for this weakness.
That's also why, for low light conditions, I was really intrigued by NiteFlux RedZone, which I guess isn't as bright as the Hotshot head on, but as a glowing red brick it's a lot more visible from all angles.
From what I've read, the Dinotte are excellent lights, but at a higher pricing tier. Almost definitely worth it if you can afford it.
As for me, I'm getting a helmet light (which have its own additional benefits). More specifically, it's the Light & Motion Vis 360+. It's not the brightest light, but with the additional amber side lights it has all around visibility.
Lastly, while I do use my Hotshot for daylight use (which should be bright enough head on), I rely mostly on high visibility clothing. This also gives you visibility from all angles.
My high visibility jersey is so bright that when I'm drinking from a water fountain in the park, the water comes out green/yellow because of the reflection. When I'm riding around the city where there are a lot of mirror-like surfaces (store windows, shiny cars, etc), I'd sometimes freak myself out when I suddenly saw a bright green/yellow thing appear out of nowhere, before realizing that it's just my own reflection.
I also have an unsightly green/yellow tinge on my face whenever I'm photographed with my jersey on, though I'm not vain enough to care about that.
Last edited by CuriousCurator; 01-27-13 at 04:07 PM.