Try explaining that to the Wife/Partner!

This forum tells me that the expected power output is similar between a 65mm SC Pulley and a 178 Crank Pulley. Any power advantage would obviously come from stacking them together.

As for other advantage, it would likely come down to how much of the engine is utilized to produce the power and what effect that has on wear 'n tear.

I don't have an oversized Crank Pulley, so the SC Pulley makes sense for me if I want more power. The advantage is that it's less expensive to acquire and is easier to install.

It's a good question you make. Puts it into perspective.

note: Please excuse my limited understanding. I realise you have a pretty awesome setup Sheldon!