I imagine F lounges are nice, but I don't see many other ways OP benefits from not being a CX GO in this scenario. In particular, is use of the F lounge more valuable than the cash OP might save using the seat guarantee, the foregone AsiaMiles from credit card spend (or the problem of having flight miles in one account and credit card miles in a different program) and the occasional op-up OP is more likely to get as a GO than as another carrier's emerald?

As with most things FT, it is a judgment of what the individual values. I would only caution against the FT tendency to assume the highest-possible status is necessarily the best in each and every circumstance.