There has been no running changes to the RS since its conception. You may be hearing of more failures since the amount of RS users has grown exponentinally over the past year.
If you see led's 12 and 67 and you have the RS hooked up to a KNOWN good brushless motor than the speedo will need repair. The sensor cable has NOTHING to do with this led sequence, only the 3 motor wires.
In regards to Tekin speedos and drag racing, what's your question?