I think it's a really sweeping generalisation to say that discs are lightest - I think the arrows are the wrong way round....?
Generally cantis and V's are about the same, with discs generally heavier - extra on the hubs, wheels need longer spokes, rotors, hydraulic cables etc.
If you want to stay alive on the trail ,then discs it is
but if you want to build a nice original specced MTB from the 80-90's, then canti's or v's would be right and proper
I think this is important on a site dedicated to older bikes
Yes, no question about it Better in every way - power, modulation, reliability, ease of set-up, and I don't think that something like Marta SL's give much away weight wise either.