The definition was in 240-3(e) in the '99 code. There is no change in the application of the tap rules. The conductors in your example are not taps per the definition as they are service conductors. I see no problem with your example as long as the conductors leaving the trough have an ampacity at least equal to the OCPD installed in the disconnect. Of course the six disconencts would have to be grouped and nearset the point of entrance of the conductors.