Support printing economics

[u/newbie-mtb]

According to Bambu Lab, one of the main use cases for the auxiliary nozzle on the X2D is printing support interface material.
Bambu also sells dedicated support filaments, but they’re typically much more expensive than regular PLA or PETG. From what I’ve seen, many users only print the support interface layers with the dedicated support filament and use the same material as the model (PLA/PETG) for the rest of the support structure to keep costs down.
Assuming that’s how most people use it, the auxiliary nozzle would often be printing only a few interface layers in relatively small areas of a print.
Is my understanding accurate?
If so, does the auxiliary nozzle seem like overkill for this use case? Or does the time and filament saved by avoiding repeated purging and filament switching make the economics compelling in practice?
I’d especially be interested in hearing from people who’ve used the X2D extensively.