The divergence from platinum to a new metal such as Zalium for this watch in its gestation must first be taken into account.
Historically, the first Oceans from HWRT were platinum.
Taking this into account, I would go for the RG. As it would be "logical" that the metal was chosen for color, otherwise I would not expect HWRT to have compromised WG for Pt.
However, on creating the Excenter during Max Busser's time, WG was used extensively thruout the range. It seemd to have a better texture after finishing/polishing, that matches the brushed finish of the dial. So this you can see on the dial of your Ocean Chrono.
The early HWRT Ocean line did not have the same brush finish dials.