It seems some comments are coming from people who haven't used a MILC with a decent EVF.
Higher end mirrorless and EVFs are at the point NOW where they are comparable to many consumer/prosumer DSLRs in performance in most conditions, including low light. Give them another year or 2 and they will likely be on par with their mirror-flapping counterparts. .. And then they'll exceed them.
The EVFs in current Olympus and Fuji cameras are impressive and I'm sure Sony's are comparable as well.
They're OLED, so have very good dynamic range and color gamut. Lag exists but in some of them, like the Fuji XT1, it's quite minimal in decent light and not bad in low light either.
I attended an event last nite, turned out to be a dim and poorly lit club. I wanted a compact but reasonably capable camera with me. So I grabbed an old Fuji XE1 over a Pentax Q because I wanted an EVF. Unfortunately, I grabbed one I'd just bought used so I had not yet set it up the way I liked. As it is, I barely use the XE1 enough to be partly atuned to it so there were plenty of shots I could have done better using more familiar gear. It didn't matter, this was not a job.
I used the 27mm f/2.8 pancake prime on it; very light, small and discreet compared to any sort of DSLR.
The XE1 is slightly older tech already, and it still performed better than I expected and certainly was no worse to use than a small pentamirror OVF in a consumer DSLR. Actually, it was no problem framing and composing images in low light where I had to use iso 3200 or 6400 at 1/15s and f/4.
AF performance was not great but it was still possible to do a good manual focus using the magnified live view in the EVF fairly quickly when needed. I don't think many consumer grade DSLRs would have had much better AF performance on the dark and low contrast targets I shot anyway but they may have been a bit quicker for focus and recompose or some of the moving targets.