There were significant changes made to DataStore API between 11.3 and 12.0, so definitely be prepared for surprises. After 12.0 I can't recall any major changes except for bugfixes.
I haven't compared DataStore with WXF in terms of speed, but I can confirm that at least for passing a list of Strings to/from Library DataStore is significantly faster than WSTP. If you decide to benchmark DataStore against WXF please share your results.
