I personally own a Nikon System with Olympus being my sub system. My D3200 was mainly for high MP work while the OMD is for street and general shooting.
Nevertheless, this still remains the age of DSLRs, though the revolution of mirrorless cameras is currently under-way. There are times when I still favour a DSLR and here are some reasons I do bring my DSLR out.
Somehow, I still feel that handling on a Nikon DSLR is better, despite the D3200 being simply an entry level body. Being able to tweak everything on an OMD is really nice, but the small body with the strap lugs digging into my palm or fingers really don’t cut it (forgive the pun).
A 3200 with a small prime like the 35mm or the 50mm is still a very compact package. Somehow, this set just sits in my hand really comfortably. Even if you do have large hands, the pinkie can be tucked under the camera for a 3 fingered right hand grip.
2. Pixel count
Say all you want about high megapixels being terrible in light, but when you can shoot in good light, having more MP is rarely a bad thing. If not, why do people bother with high MP medium format? That extra 8 MP means that extra bit of cropping allowance. Also, i do have the lenses which allow me to resolve that extra bit of detail. Bringing me to my next point.
I was already a serious Nikon shooter for some time before i dived into M4/3. As it stands, i own a small arsenal of FX lenses and quality primes for the F mount, compared to 2 small primes for the Olympus, the 14mm 2.5 and the 45mm 1.8.
The AF on the OMD and the two primes are fast enough for most people, but nothing beats the feel of the lightning fast AF of the Nikon 24-70 2.8, even on the entry level D3200, and the images that pop out of the camera.That being said, take note of the tremendous price difference between just the 24-70mm ($1800 second hand) and the two primes($450 for both). Also, I doubt if most people really need that extra burst of AF speed offered by the professional grade lens.