When I first tried to tackle the WS2812 signal's degradation over long distances the plan was to use an ATiny2313 on an RS-485 bus and send packets from the Teensy to the ATiny which would then control the LEDs.  I chose the 2313 so I'd have to work with limited resources just to add some fun.  I had things working well with a lightweight message protocol and the rs-485 running quite fast.  Then I had the realization that maybe I could just run the ws2812 direct off of rs-485 transceivers.  Like magic, it worked great.  A lot of work went into the ATiny stuff that will remain unused, but it was good to learn anyway.

 Since I'll be running point-point direct from the Teensy to an LED strip and then from one strip to the next, the protocol is RS-422 instead of the multi-point RS-485.  Transceivers typically do both, the main difference I noticed was that the differential lines are terminated with a resistor only at the receive end.

A month or so after working through the new, simple solution, this link showed up on HaD: http://www.teknynja.com/2014/02/driving-ws2812neopixels-rgb-leds-over.html