Welcome Arvid. The D3s is a tremendous camera, and I really miss my D3 at every mention I read of one. Personally, I would say you made the right choice going for this camera over a mirrorless, even if many here would disagree. It's just a matter of how the camera fit's the hand and how incredibly nice the view through the D3 viewfinder is.
Years ago, back in art school, I chose to study photography. At the end of the first year I showed my interest, and I was invited to be in the room next to the fascilities darkroom the first day of the next semester.
I entered the room, and the professor was visibly disapointed. Not only was I the only student for that year, but as he kindly pointed out, photography clearly wasn't where my talent was.
I told him: "Those are my thoughts exactly, good Sir. I already know I can paint and make illustrations, but photography is a field where I really can learn new things"