Not 100% on how this all works, but I do know that once I get to about 40 minutes in, a replay becomes aggravating to work with, as it takes quite a while for it to catch up when rewinding.
Is it possible to have replaymod create either some key frames, or create a new replay after x period of time?
Recording UHCs is a pain because I have to relog every 40ish minutes, and people really frown upon people doing that too often during a UHC.