I have just enabled the default changelog in my directory service (2.0.0-M1) and get a npe from the MemoryChangeLogStore.loadChangeLog method when the directory service is restarted. This is happening because the method is called in init before the directoryService field is set.
I have raised the following issue for this:
There is a fairly simple workaround, e.g. delete the changelog.dat file prior to restarting the service.
I realise that this part of the service is still work in progress but I thought I'd raise it to keep visibility.