Re: OM-D E-M5 New in Box!
I still use the E-M5, and I have about 45k clicks on it. Its definitely a great camera, and to be honest, the sensor is still current generation. Basically, all the new cameras have extremely similar sensor performance, which is why I have been reluctant to upgrade.
There are no substantial firmware updates, so while you can do it, it won't really change much.
The best thing about the four thirds system is undoubtedly the really small prime lenses, which really drive home the size/weight advantage. Have a look at primes such as the Olympus 45mm f/1.8 and Panasonic 20mm f/1.7.
Olympus E-M1 Mk II
7.5mm f/2.0 - 17mm f/1.2 - 56mm f/1.4 - 9-18mm - 14-150mm II