D4 to OMD-EM5

Also, the E-M5 takes forever (compared to a DSLR) to wake up from sleep mode or to be ready to take a photo when you turn it on.  2-3 seconds.  If you need to shoot quickly you will lose shots compared to any DSLR (not just a D4).  Reviews almost never mention this although dpreview and others always made a big deal about it a decade ago with cameras and that is why DSLRs got so fast, but they don't talk much about it with mirrorless.  It is an area that needs a huge improvement.

--
Henry Richardson
http://www.bakubo.com