We'll definitely need to play the new updates to see if it's the better option. That'll be inevitable, but I think it'll take longer given the new locations and enemies, QOL fixes, balance changes to attacks and items, everything.
There might be a possible way to still incorporate older version runs through the Steam version of the game. It isn't a guaranteed solution as this would require testing, but it's important to consider.
I want to avoid (publicly) distributing various full builds of the game, as that's piracy. Random users go to our resources page to download the entire game without paying a penny. But this seems to be the only legal method of accessing previous builds.
https://www.makeuseof.com/how-to-downgrade-steam-games/ (This is the original source with written instructions. The video description provides links to all the necessary downloads for downgrading Steam games.)
And given the ability to easily make back-ups and to decrypt RPG Maker MV games through multiple methods (https://petschko.org/tools/mv_decrypter/), we could independently create executables for v.1.9.1, v.2.0.0, v2.0.1, etc. and keep old runs active while also still allowing those to be active categories.