If, with the settings you like in a scenario in which you normally fly, MSFS Developer Mode FPS view shows you are GPU limited by a reasonable margin (ie. 30%+ longer frametimes than mainthread) then yes it should be worth it.
eg. in the screenshot below, GPU frametime is 38% longer than mainthread, so a GPU upgrade would be warranted in this case. The greater the frametime gap, the more beneficial a higher end GPU model upgrade will be.
