I prolly have just about paid for my Cascade in teh amount of use i get out of it, almost everyday its running which I could not do with LN2. I save that for chips that can really use it and for GPU's when I run them.
To say nothing about ease of use. You can walk away and do others things when the MonstaCade is running and not have to worry about the pot running dry. Being able to take your time in tweaking is also a big plus.
It has not taken away my need for LN2 to tho, just made things much easyer.
How ever, colder is better