Regarding the "120Hz dance", which sure is ridiculous, the author could probably give the nice little tool "SwitchResX" a try. I adore that piece of software because it allowed me to force my MacBook to properly supply my Dell U2711, which is a 2560x1440 display, with an actual 2560x1440x60Hz signal over HDMI (which was important to me because I needed the DP port for something else).

That older monitor has some kind of firmware bug or maybe it's a wrong profile in MacOS or whatever, which makes it advertise a maximum of 2560x1440x30Hz or 1920x1080x60Hz to the Mac when connected via HDMI (DP works fine out-of-the-box), effectively preventing me from choosing native resolution at maximum refresh rate. I haven't been able to make MacOS override this limitation in any way using the common OS-native tricks, but SwitchResX can somehow force any custom resolution and refresh rate to be used, and the monitor is apparently able to deal with it just fine, so I've been running this setup for years now with no complaints whatsoever.

Also no manual work was ever needed after display disconnect/reconnect or MacOS reboot. I had problems once after a MacOS update, which required a SwitchResX update for it to be working again, but other than that I'm in love with this nifty low-level tool.