Considering trading Tamron 70-300 f4-5.6 for Tamron 70-200 2.8 or Nikon 70-200 4.0

So after getting my Tamron 24-70 2.8, I really like having a constant aperture. Therefore I'm considering trading my Tamron 70-300 for either a Tamron 70-200 f2.8 or the Nikon 70-200 f4.0. Basically I'm willing to give up some focal length for the constant aperture. My photos are general (people, scenery, events, etc.). I took some outdoor photos of my daughter and her prom date recently with the 70-300 but felt somewhat limited by the variable aperture when trying some different shots.
I like the concept of the 2.8 on the Tamron for darker indoor events but the smaller dimensions of the Nikon are appealing. I'm also keeping in mind that someday I will most likely upgrade from my D7000 to either a D7XXX or something like a D750.
What are the pros/cons of the Tamron 70-200 F2.8 vs the Nikon 70-200 F4.0?
Thanks.

I shoot most my portraits as wide as possible. Without going into the quality of both lenses, I myself would pick the f/2.8.

For other subjects it is less important.

To add: the last two photos I posted in "portraits" are shot with the Tam 70-200mm f/2.8 (new version).

My Tamron 70-200mm f/2.8 practically lives on my D750. It's an amazing lens.

One of the portrait shoots I did with it was with a dancer named Ghenna but that shot alone doesn't really the Tamron a proper justice.

I use my Tamron 70-200 f 2.8 even when I probably should use something else. LOL

I even have the older version and if you have the funds I would recommend the newer one as the only complaints are that it will hunt a bit but even at that, a great lens.

So the more I read, the more I'm thinking the Tamron would be the way to go (2.8, image quality, price). My next question is what are your thoughts on its weight? I don't spend hours walking around with my camera; and if I am walking around I usually have a shoulder bag. I've adapted to the weight of the 24-70 just fine and sometimes feel like its heavier weight helps me steady the camera. I do have a monopod and was thinking it might be good to use with a 70-200.