Ok, but even 60/40 does increase the amount of light in the viewfinder/lightmeter by only 0.73 stop. Which easily can be compensated.
Yes, it can.
However, take into consideration that a very good amount of EC is often required to get good exposure with manual focus lenses to begin with. The extra light from a 100% silvered mirror will just exacerbate the issue, so it makes sense to try to compensate for it in the way that I have described. No?
