Snow has been around for quite some time and I have only heard good things about their kits.
Absolutely required, a gauge or light to tell you when it is running, one to tell you if out of fluid, one to tell you if a fault.....I have seen setups that would limit boost automatically if it runs our or fails, plugged injector, etc......
I love the effects of using it but not the added complexity thus more to keep track of and more to go wrong....
If you do use one find a place you can get a 5 gallon jug refilled to save some money and carry a little extra in the car when going to events, etc......