The Nikon 105mm macro isn't too heavy.For D750 I use: Nikon AF-S Nikkor 14-24mm f2.8G ED for most things, along with the Nikon AF Zoom-Nikko 80-200 mm F2.8D ED. Sometime the 50 mm prime. I also have the Nikon 200mm f4 Micro lens, which is a total beast to carry around, and a 28-300 Nikon lens.
All the Olympus gear combined doesn't weigh what Nikon Micro lens does.
But it's a beautiful lens.