Thanks. Frankly, the reason we have a separate fork is because some of our changes to rrweb in the early days were "hacky" to the say the least, and given that their team is part time on the project, there was occasionally a long cycle to get changes in.
We do have plans to consolidate one day, and I understand your sentiment about making diffs hard.
Fwiw, even beyond sponsoring the project, we even sponsored some folks on their team to work on particular features in the privacy and webgl space, so we have a really good relationship at this point.
I'll talk to the team regarding consolidating at this point. I appreciate the message.