Cold light heads are usually not so bright as condensor or diffuse light sources therefore exposure times are longer. The same negative printed on cold light will be about 1 paper grade softer than if printed on condensor. IMO the bit about the density of the negative is total rubbish. Small blemishes such as dust etc on negatives will be less noticeable when the neg is printed on cold light, it's something to do with the difference in the way the light is scattered by a condensor. Another myth IMO, is that you can use a regular cold light to print using VC paper and compensate for the fact that the colour of the light is blue by introducing extra yellow filtration. To print VC you need the green and blue light source like the Zone VI that I use although I understand that Aristo do make a VC light source that is very good but not like the Zone VI.