Mirrorless camera is not a dslr, so don't expect it to perform like one, especially in af speed, response and even the start up time you were mentioning. But the image quality these days in mirror less is good enough to replace a dslr on certain extend.

I guess most of us here are from dslr league. So when choosing a mirrorless system, we be more cautious as we want the best out of the system. Each system has its advantage and as far as I know you can't get the best of both world. Example like Olympus is famous for its in body stabilisation and weather sealing, Panasonic has its GM1 for smallest CSC contender and the noctilux, fujifilm has it unique x trans sensor and retro styling, Sony has blazing fast af speed and zeiss lens as stronghold.

So when I buy a mirrorless, I wish I have all the wanted stuffs as I said above. So for me any system will do, as I will eventually suit to the system and get my photos out of it. Quote from my sifu: "a good photographer should able to make good picture with the gears on hand and not relying on hears to make good picture."

Anyhow, happy shopping!