One, or two frames out of a day's shooting doesn't magically change the fact that ANY EVF has "some" lag, while an OVF is working at the speed of light.
EVF's are getting better, yes, but for example, the Sony A7's EVF is what really put me off from actually pulling out my credit card and buying it. The camera body itself is reallllly neat, and the lenses-on-adapters possibilities for the A7 and A7r were really intriguing, but I could not clearly see the FACE of a man standing 6 feet away through the EVF...not well enough to judge the expression to know whether to shoot, or not shoot. To me, it's the difference between "learning how to compensate": for a poor viewfinder image, versus actually being able to SEE, at the speed of light, exactly what the subject is doing in real-time. Still, the A7 series is nifty technology. I can understand why people like it, despite the current lack of AF lenses for it.
A really honest discussion of the pluses and minuses of the EVF versus OVF is kind of beyond the scope of this forum, but the information is out there. Still, there are a lot of nifty mirrorless cams out there. This weekend at the seashore I was asked to take some photos of a man and his wife with his Olympus PEN EP-5, which we talked about afte the session; that camera is ALMOST EXACTLY the same height and width as my iPhone. A little bit "deeper" though, front to back, but still a VERY small body, and the 14-42mm zoom was also very small. I realllly liked the SIZE of the Pen EP-5 and 14-42mm zoom! Sooooo small!!!! Soooo light!!!!
The rear LCD on that small Olympus was decent, even on a fairly bright beach. To me, THAT's the size that makes a mirrorless a go-anywhere type camera. I deliberately left my big Nikon and its various lenses at home, and carried just an iPhone, so I could enjoy the beach experience with my son. And I did get some decent photos, but still...I think photographically, the "real" mirrorless cameras might be a better choice for more-serious photos. I feel like I could have done better photos with that Oly EP-5 and 14-42mm zoom than with my iPhone 4. There are a lot of neat cameras on the market; Fuji, Panasonic, Olympus, Sony, Samsung...they all have some nifty offerings. I just think the Sony A7 is NOT really going to be a carry-everywhere camera because....when they DO get the lenses out for it...those lenses will still need to be lenses for full-frame 24x36 coverage; iof I wanted a go-everywhere rig, I would look more at the really compact bodies with the really compact lenses. If I wanted a carryable, go-anywhere, interchangeable lens camera, I would not really WANT a full-frame sensor in it for my zoom or tele needs. Fuji's idea of APS-C sensor size, with a single, like 23mm lens makes some sense, but I really think the smaller bodied mirrorless models would be easier to carry than an A7 full-frame mirrorless.