pithydoug - you don't undertsand.
With a mirrorless you have liveview in the viewfinder (EVF or 'eye piece' as you call it) all of the time. The histogram is in the 'eye piece' before you take the shot. I can toggle through various displays in the 'eye piece' to show the histogram, all of the settings, focus peaking, highlight zebras etc all without taking my eye from the eye piece which I have adjusted to my eyesight without glasses. I can also just show a clear screen of course. Having the histogram in the 'eye piece' means I can adjust the exposure to avoid blow highlights or decide if I need to bracket the exposure without having to take a test shot, chimping and adjusting. I just check the histogram and turn the exposure compensation with my thumb until the graph just touches the right hand side (or a little beyond - but that's another story). After I've taken the shot the review comes up in the eye piece. I don't have to put my glasses on to 'chimp' to the rear screen to see what I just got.

To me - that is the real benefit of mirrorless over DSLR. The size and weight is a bonus, but being able to do everything without switching glasses on and off is the real beauty.