Been using SyncBnB for over a year now. It does sync my calendars between various channels without any practical delays. Support is great as well and they're open for suggestions. Haven't tried the new rate management feature yet, so can't comment on that. Seems very interesting. When syncing occurs, dates are blocked as expected, however, not all data is consistently synced. At times I compare the data with their source and amend it here and there in syncbnb.