Hmm, I just see repeated marketingslogans... but let's check some points...
>Autofocus can be much more accurate and work even with small aperture lenses.
Wrong. The more accurate AF is just because you use contrast based Focus, you can do this with DSLRs, too. It's called liveview. On the 70D even in Dual-AF.
>They can be made smaller lighter, and shock resistant.
Lighter is true, smaller... maybe, with the given limits and a new design. Shock resistant? I guess a 1DX is more shockresistant than any Fuji. Where do you get such claims?
>They use fewer moving parts, and will be more reliable
The mirror-based technology is grown up since more than a half century. Photographs felt in vietnam, got shocked by earthquakes or took every sport-activity you could imagine. Do you really think it's the weak spot of a camera? Especially with semipro business or amateur? Why is there a shuttercount but no count for a mirrorlifetime? Right, even the shutter dies before a mirror does. And the shutter is still there, most likely a cheap one.
>The complex moving mirror, sub mirror, pentaprism, viewfinder, AF sensor, and light sensor cost quite a bit, so mirrorless is potentially a lot less expensive.
Calculate again with the required EVF.
Fuji with its X-mount platform designed with a 17.7mm flange-sensor depth (the back of the lens is even closer to the sensor by 7.5mm) manages to get some terrific image sharpness with almost no chromatic aberrations all across the frame. I find that my X-T1 with the XF56/1.2 delivers better images overall wide open than my EF 85/1.2LII stopped down to 1.8 on my 6D...
First of all, the 56mm 1.2 *has* CA, even they're quite decent. But if you read my text again, you will note that you get problem in the wideangle-area. I don't think 56mm are wideangled.
It also opens up the possibility of FAST burst rates like 30fps.
Not a problem of the mirrorbox. You can do this with any DSLR, too. A DLSR with Mirror open *is* a mirrorless. The only difference is a blacked out viewfinder, but you could compensate this the same way the mirrorless does (EVF/LV).
Mirrorless has only advantages
I think people are just repeated the Sh*t they read in the magazines. This is just another pig, chases through the village. I'm not of yesterday or want to nag on anyone in this forum, but please open up your mind and think for yourself. Compare the new trends with the translucent mirror of Sony/Canon or Rangefinders. They all prayed their advantages and they truly have. But always see what's the *real* benefit of it. I just see the advantages in weight and maybe the size if you create a new camera with full take of the advantages.
Remember, the size has sideeffects. The accus are small and you carry 2 or 3 of em with you (300 pics CIPA with a Fuji-XT1 is a darned cheek). And if you want a nice handling you make it bigger with a vertical grip. Then count your bag-weight again.
The cam is a tool, not more. If a mirrorless does it for you, you should take it. For me, I'm not convinced. Not after I thought twice.