The hz of the screen and fps are not the same thing, so even if you're not hitting 144fps it should still be better. In saying that you get the real benefit when you can maintain more than 144 so you may need to start running a similar setup to me. Textures and Mesh on Ultra, everything else low/off.
You could sell that 780 and get a 970. Locky tells me both of his Gigabyte Gaming cards do 1500 24/7 and at that speed they are faster than his 780 Ti @ 1200 which will give you a massive boost over the 780. EDIT: We're running difference resolutions so performance is not directly comparable.