You will get a bit more and smoother blur. If it's worth the Investment is up to you. But be adivsed that the smoothness of the blur is highly depending on the lens-construction itself, so the numbers only say so much
Calculating the DoF, and the Bokeh.
In this Screenshot of the Software cBlur (a german online version exists here), you can see the Sharpness-curves for a 50 and a respective 85mm lens, set at the same aperture (f/1.8) and focused on a distance which covers the approximate same object height in the image (190cm, which is roughly a full body portrait).
As you can see, the circles of confusion are higher for the 85mm (blue line), which basically means more blur. In the online version, you can also get example image of the approximate blur. (Which does NOT equal a higher bokeh quality, because that also depends on contstruction details of the lens).
From my personal experience with a 35mm and a 56mm prime on a Camera with Crop Factor 1.5 (which equals your Nikon DX) set to the same aperture (1.4), for Portraits with only head or head and shoulders it's irrelevant (though the 56 has less perspective distortion and makes "nicer" faces), but on a full body portrait, the 56 has more blur. But you also need a lot more space, which may not always be available.
A note on artifical bokeh
Creating a Bokeh in Photoshop or "Blurring Backgrounds" is not an easy Task and requires Depth-Information, which you don't have in a 2D Image (that's why e. g. the iPhone 7 uses two cameras to create an artifical DOF effect, and event this doesn't work perfectly).