"I am not completely sure how replays from an earlier build will work in this version."
Just tried it out. I imported the DMK_Saves folder from YukariWIP 1.0 to 1.2
It didn't work. It desynced at the first slalom nonspell.
(I compared to my 1.0 recording, the pellets didn't spawn in the same fashion somehow. Even though they all seemed to be normal in the previous phases)
I also went for a run in v1.2 just to make sure its replay works. Seems like it does work properly.