In a recent Grapevine article I read of a longitudinal study that shows a direct, positive correlation between AA-related helping and sobriety.
Maria Pagano, PhD. developed methods to quantify and measure service work and related AA-helping (sponsorship etc). She also conducted in-depth interviews with AA members with more than 20 years of sobriety. (That is us out-of-the-woods folks). Her research found that AA related helping to be important to early recovery and in long-term recovery as well.
This is helpful to remember as many of us know that service is good for newcomers but may have shifted our volunteer or service work in later years to causes outside of AA.