Ok, on some serious note here: I have had Fuji GW690II, Hasselblad 500c/m, still have Mamiya C220 and Pentax 67. Each had its own benefits and quirks. But when people on the interwebs talk about weight they seem to forget to include a benchmark. What are you comparing it to?
1. Fuji GW690 in all 3 versions is rather light, it is about the same weight as your plastic 35mm SLR or a bit heavier. It is very ergonomic and easy to use. Only 8 shots per roll of 120. Loud shutter sound.
2. Hasselblad 500 is a great system camera, rather dependant on CLA, many components can go wrong, very expensive system. Weight is probably similar to metal 35mm SLRs, but lighter than Nikon F2. Very good travel choice. Sounds boxy when tripped.
3. Mamiya C220 is a bit lighter and smaller than C330, about the same size as a Hasselblad, same weight approximately. Sounds very quiet. Extremely nice for travel.
4. Pentax 67 is the biggest one out of these, also the heaviest. Weighs the same as a Nikon F2 with a lens. It's not too uncomfortable to carry around all day, but you will grow a muscle. Very easy to use, sounds like a shotgun with reload. 105mm produces some of the most 3 dimensional looking images I've seen out of any of the cameras I've listed. Mirror slap is grossly overrated in the myths of the interwebs. I am taking it on a vacation to California and will see if it's a good travel buddy.