I find having favourites menus very handy.
Also the L Fn button on the lens seems to have more options if I remember rightly. I can e.g. set it to C1 where C1 is set up for C-Af with tracking - not sure if you can do that on the EM1ii. Perhaps you can. You can also set it to limit the focus distance - also handy in some situations.
Being able to hit the joystick to set the 'home' function is good too - I've only just realised for example I can toggle between a 3x3 grid and with that and single point focus.
Performance wise, I don't think I have noticed a difference really.