In short, yes. While humidity does have an effect on savings, Mistbox users should expect to see an efficiency boost between 20-38%.
Mistbox users in mild, humid climates can expect savings in the lower end of that range, while those in hot, dry climates can expect to save more.
While efficiency may be lower in mild, humid climates, Mistbox users in these regions can still expect to save a lot because they are likely running their AC the majority of the year.
The more you spend on your AC, the higher your potential savings.