You can use both the new Store & Forward + Historian API; while the Historian API is decoupled from Store & Forward, you can still create your own DataSink and register it against the Store & Forward engine (for your connection that needs persistence durability). The only issue is that the Historian's TemporalPoint data model is not an extension of PersistentData (Store & Forward's data modeling). What you'll end up having to do is use the bridge classes contained within the Historian's API interop package, which allows conversion back and forth between the new Historian API and TagHistoryData for Store & Forward purposes.
Also check out this post for a bit more of an overview: Historian SDK API Changes in Ignition 8.3.3