biggest problem is that this is a 2 way street - there are no inherent disadvantages or advantages to mirrorless vs. reflex.
Here's my list of advantages, which has some overlap with AvTvM. Essentially, it's all the advantages of mirror, plus the advantages of LiveView. I'm assuming EVF here.
- The mirror mechanism is a design constraint and a potential point of failure. Leaving it out could simplify design and construction, possibly making it more reliable and less expensive.
- You see what the sensor sees, so you know that what goes in the image file is what you saw in the EVF
- Histogram, blinkies, plus all the features of Magic Lantern: zebras, focus peaking, etc.
- Select AF point(s) anywhere in the frame
- If eye control is possible, then it could be used not only for controlling the point of focus, but also to turn on/off blinkies, zebras, focus peaking, histogram. You could set up your shot without taking eye from eyecup.
As Neuro said, this is also possible with a pellicle mirror. Also, I differ from AvTvM in that I'd like to keep my primary camera at the size it is (60D), and keep using my EF lenses. Small is not essential for me.
And that's all mirrorless is now, a gimmick, a toy camera for those that want a little more than a cell phone but not willing to learn enough about photography to invest in a trusted system.
That seems harsh and disparaging to all those who use LiveView. A lot really good landscape photographers have publicly stated that they use LiveView.
what about ergonomics?
There will be a variety here, no need to worry about all mirrorless cameras being the size of the M. Besides, even if it is, someone will make a "grip" for it that will make the ergonomics whatever the market wants.
I'll say it again, why redesign the wheel???
Iron-rimmed conestoga wheels gave way to solid rubber, which gave way to pneumatic tires,
which gave way to spinners,
which will give way to personal aircraft. Each tech lives its life, then is left behind for something better.
There are so many amazing lenses that are made for slr mount bodies. Why put resources into redesigning these amazing lenses to be smaller when you could just take that out of the equation and focus on making a better, more viable mirrorless body?
Again, no reason there can't be an EF-mount mirrorless.