Well with spray cooling you don't even need a heatsink. The advantage is that it can handle extremely high heat loads 90W/cm2 is possible and with subcooling that can reach 300W/cm2 or more. So pretty much insane power densities that would cause the component to melt with air cooling.
The disadvantage is that spray cooling requires some pretty incredible precision and if anything fails the chip will die in a matter of seconds (if that). IMHO immersion cooling is already pretty complex as DIY project anything beyond that is starting to get into a serious engineering challenge.
I guess my point is that with a heatsink and spraying, maybe you don't need the FC-72 because the liquid only needs to touch the heatsink and you don't have to worry about shorting things out. But yeah I can see the requirement on precision and complexity. It may not be worth it for a small scale shop.