Well, whilst I agree that the Nikon (or Nikkormat in my case) and the Leica (M6 in my case) are almost equally heavy as camera bodies, the minute you start adding extra lenses to the mix the weight and bulk factor starts to favour the Leica. Unless the trip is oriented towards car travel and there's not too much walking around then the weight of the Nikon kit can see you getting more and more reluctant to haul it around.
Frankly, my own travel kit now is basically the much lighter Bessa R4A for B&W and the Fuji X10 for colourful 'snaps'.