Based on testing with DBC's back in the day, you should expect 60-70ft. The bigger question is how long will the 3mm LED last - Phil did a lot of experimentation with the limiting resistor on the DBC to stretch the LED that far without blowing it on a regular basis. How long the LED lasts with another board, which assumes a 5mm LED with a higher tolerance for current spikes, is going to be an interesting question...