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EVF is not yet up to the standards of opticla VF as a way of looking at the scene you want to capture - whether you think the differences are important is personal preference.
EVF has its advantages WYSIWYG, peaking etc) - whether you think those outweigh the EVF disadvantages is personal preference
That is true, there are tradeoffs.
There are also a couple shortcomings of OVFs too.
Overall I'm finding EVFs provide me more useful functionality than OVFs in almost every situation. So much so I don't even notice any drawbacks to using EVF any more .. unless I'm trying to use one of my old Fujis at night with no light source in the scene.
Mirrorless has the capacity for a smaller system but whether you like a smaller body with big lens is personal preference
The sizing options are not all that dissimilar to putting a big heavy FF zoom on a small crop body SLR. You can make any system somewhat unbalanced with the right combination.
I have comfortably large MFT bodies like the Oly EM1 (w or w-o battery grip) which handle nicely with larger pro series lenses (which are considerably smaller and lighter than comparable FF glass for equivalent FL) and still doesn't feel too bad with small primes.
OTOH, I have small MFT bodies like the Oly EM10s that are very light and compact yet just large enough to not feel cramped when using them. They work well with the small light kit zooms and mid-range primes.
The Pen series, w-o EVF, combined with pancake lenses are smaller still... TOO small for my liking but some people do like them.
So I don't think there's any hard argument against ML systems being physically too large or small. They've become diversified enough to cover quite a range of body and lens sizes so how you choose to combine them is really not much different from DSLR and lens selections.
Nothing's quite as big as a 1DX tho! That lines up well with an 800/5.6 lens which would probably tear the mount right off a Rebel body if you tried to carry it by the grip. LOL
That said, I do find Sony's ML FF bodies a bit too small to feel comfortable with a large lens on them but ... that's Sony. They made all their bodies about the same, physically, so didn't leave buyers with much choice vs all the other ML mfrs who produce a variety of designs.