The fins look great but barely drop the fluid temperature. And even if it did...does it matter?
These systems are engineered to operate with different loads under a wide variety of circumstances. Banks puts together a nice video although when I watched it I do not remember there being any earth shattering information related to lowering the temperature of the differential fluid and how it significantly extends the life. My suggestion is that if you are truly concerned about extending the life of your drivetrain, visit your local dealer every 60k miles and have your transmission, transfer case, and front and rear differentials serviced for around $1k.
Nice video though...