While looking around for the 4DLite Plus for this thread, I saw this:
They call it a Toplight Line, with a "LineTec" lens for its two LEDs. I think it's supposed to give better dispersion side-to-side but, more importantly, instead of appearing as a single point of light, it looks like a bar of light, which should help onlookers better estimate your distance and speed.
I like my Selectra ( http://bumm.de/index-e.html?docu/320e.htm ), but this new one looks pretty cool. I'll see if I can get a hold of one in a couple months or so.