Hi Greg
The surveyors's datum was WGS84 with center meridian 29 or LO29
SBAS is for all intents not available over here as the satellites sit just above the horizon and I do not have a view of the horizon
I have never used any thing else than GPS only data for my experiments etc.
It is in a RTK mode yes the datum is default as shipped with the receiver
Sincerely
Anton