I didn't include percentages for advantages, average number of successes or chances for more than 1 success, the percentage is for at least 1 net success. So yeah, advantages are important, but when shooting at someone success is "more important" than advantages, unless the goal is not to wound and harm the target, but then why shoot?
I can give you the numbers if you want, just for the sake of it:
AA DD S = success 35,1% for at least 1 success. At least 3 successes:3,4%; At least 2 advantages 7,3%; At least 2 threats 26,4%; Most likely success result 1 success; Average result 0,53 successes.
AA DD S B = success 44.1% for at least 1 success. At least 3 successes:6,9%; At least 2 advantages 19%; At least 2 threats 16,3%; Most likely success result 1 success; Average result 0,73 successes.
AA DD = success 43,5% for at least 1 success. At least 3 successes:4,8%; At least 2 advantages 9,9%; At least 2 threats 17,8%; Most likely success result 1 success; Average result 0,67 successes.
AA P DD S = success 56,7% for at least 1 success. At least 3 successes:13,9%; At least 2 advantages 19%; At least 2 threats 16,3%; Most likely success result 1 success; Average result 1,08 successes.
AA P DD S B = success 63,8% for at least 1 success. At least 3 successes:20,1%; At least 2 advantages 33,1%; At least 2 threats 9,9%; Most likely success result 1 success; Average result 1,34 successes.
AA P DD = success 65,1% for at least 1 success. At least 3 successes:18%; At least 2 advantages 23,9%; At least 2 threats 10,3%; Most likely success result 1 success; Average result 1,30 successes.
AA P DD C S = 39,5% for at least 1 success. At least 3 successes:7,6%; At least 2 advantages 12,1%; At least 2 threats 30,5%; Most likely success result 1 success; Average result 0,7 successes.
AA P DD C S B = 46,8% for at least 1 success. At least 3 successes:11,8%; At least 2 advantages 23%; At least 2 threats 20,7%; Most likely success result 1 success; Average result 0,9 successes.
AA P DD C = 46,7% for at least 1 success. At least 3 successes:10,1%; At least 2 advantages 15,4%; At least 2 threats 23,5%; Most likely success result 1 success; Average result 0,85 successes.
AA PP DD CC S = 42,4% for at least 1 success. At least 3 successes:11,7%; At least 2 advantages 15,7%; At least 2 threats 33%; Most likely success result 1 success; Average result 0,84 successes.
AA PP DD CC S B = 48,8% for at least 1 success. At least 3 successes:16%; At least 2 advantages 25,9%; At least 2 threats 23,7%; Most likely success result 1 success; Average result 1,05 successes.
AA PP DD CC = 48,8% for at least 1 success. At least 3 successes:14,6%; At least 2 advantages 19,2%; At least 2 threats 26,9%; Most likely success result 1 success; Average result 1,01 successes.
AA P DD SS = 48,6% for at least 1 success. At least 3 successes:10,7%; At least 2 advantages 14,9%; At least 2 threats 23,1%; Most likely success result 1 success; Average result 0,89 successes.
Aiming once:
AA P DD SS B = 56,1% for at least 1 success. At least 3 successes:15,9%; At least 2 advantages 27,5%; At least 2 threats 14,8%; Most likely success result 1 success; Average result 1,13 successes.
Aiming twice:
AA P DD SS B B = 62,8% for at least 1 success. At least 3 successes:21,8%; At least 2 advantages 41%; At least 2 threats 9,3%; Most likely success result 1 success; Average result 1,38 successes.
What about removing both setback dice? AA P DD = success 65,1% for at least 1 success. At least 3 successes:18%; At least 2 advantages 23,9%; At least 2 threats 10,3%; Most likely success result 1 success; Average result 1,30 successes.
So yes, if going for advantages at the cost of potential success, going for the boost die is the best choice, but sometimes success is more important than others. Still, it is a matter of prioritising and I think it can be useful. This is the fun with this system, the various axis of positive results are sort of inverted, success comes at the cost of advantage and vice versa.