Weight: system more important than sensor size?

well, I knew we were going to get to this point (and I don't like it, since people get really nervous when talking about "equivalent") but anyway:

The nikon on m43 would have the same DOF of a 200 f5.6 on FF and, since FF have 2 stops physical advantage in noise, a 200 5.6 400 ISO 1/200s will be the same as the nikon on m43 @100 iso 1/200s.

And since there's no 200 5.6 for FF, I can't compare it... I think it's the whole point of my post. Light, slow lenses just don't exist in FF. When they exist (40mm STM is one) are not that heavier than m43 lenses.

well, the 40mm is autofocus, and it's light and fast enough (it's cheap too, but that's not the point). So I don't think that autofocus is the problem.

The point, again, is that lenses like the 40mm are not "that" interesting for FF user, as they don't value the size/weight of the system as people in m43 do (and people in m43 are super-right to value the size/weight of lenses, because it's important).