Risk-averse indices were first proposed by Joel Friedman in early 80s. The importance of the risk-averse indices was underestimated and the indices were not much used in practice until recently, when the feature of risk-averse indices generation was included in SBA. The basic idea behind risk-averse indices is that when making a playing decision the player should not always maximize the expected (average) profit, but should also take the possibly increased risk into consideration. This will allow the player to use higher unit bet, and in the long run win more money by using RA indices. You can read some Internet posts to the up-to-date topic of risk-averse indices.
Simulations run by several blackjack experts, John Auston among others, show that the correct usage of risk-averse indices improves player's performance by about 3%. Now, you may think that 3% is not that much, and may not be worth the extra trouble. In general this could be true. But the point is that the 3% improvement comes with practically no extra effort! The only change is that few indices have different numbers. Today players strive to achieve extra few percent improvement and are often willing to change their counting system. Here you can reach the same improvement by just changing, say, 10 index numbers.
Kelly risk-averse indices is an absolutely unique feature that no other publicly available software other than SBA can accomplish. For example, do you know the Hi-Lo multiple decks index for doubling hard 10 vs. dealer's ten up? If you say +4 then you are only partially correct. This is the expectation-maximizing index. However, it is not the optimal index. If you take the risk into consideration it turns out that the correct index is +8, which is quite a difference! This is true unless you are from some reason underbetting. Or, did you know that it is NOT correct to split 4,4 vs. 6 up for true counts greater than +6, DAS allowed? The correct alternative is hard doubling. The reason why this is so comes from the fact that hard doubling is less risky than splitting with DAS, and this lower risk is more significant than the small loss in expectation.
The Kelly risk-averse indices, which SBA can generate, are the optimal indices that one should use. An exception could be a high roller who from practical reasons cannot bet as much as he would like to. Such a person could use the expectation maximizing indices rather than risk-averse indices. Optimally, such a person should still use risk-averse indices but set 'Aversion ratio' in SBA to some value greater than one.
If you want to read more about the risk-averse indices, you can read a detailed explanation in the Explanation of Blackjack Statistics book, which is a part of the full version of SBA. You can also post a question on any of the Internet discussion groups.