Some interesting comments raised here. I for one will fit sound to my 4-TC if an appropriate chip is available, I also enjoy lighting and running stock in various lighting conditions. I do agree with the comments on the incorrect temperature of lighting so often used.
As for DCC, I use ZTC systems and enjoy the ability to drive the locos correctly, not just have off, on, faster etc that DC offers. Real trains need brakes, have inertia etc, which can be enjoyed under DCC,
I am also not quite sure why it is believed that DCC stops block signalling etc. - no it does not. See http://www.blocksignalling.co.uk/index.php/block-occupancy-bod1 for example. Have your signals set automatically and drive accordingly under DCC - simples.
Roy