In my opinion, its simply the wrong question to ask, or the wrong attitude to take respecting the sacrament--that somehow the child baptized has more likelihood of salvation, or of being elect, yada yada. It's all barking up the wrong tree.
The blessing is totally in how one receives the grace exhibited in the sacrament BY FAITH. For the infants, the appreciated blessing comes when/if they accept the reality of the signification by faith. Meanwhile, the church has been blessed even before the child has, through the application and observation of the promises-made-visible, and through the "right use" of baptism in its "improvement" by those present and already baptized.
It is always beneficial to perform our rites as God has prescribed them. It is always better to perform them as instructed than contrary to that instruction. But to focus on the ritual as though such a thing in itself has force to make probable or predictable (%) the saving of a soul is to misuse the sacrament.
Would anyone say such a thing concerning an adult? Would we point to an adult baptized, and dare to say: "This proves it more likely that this person is a saved individual, than that he's not." That is not the purpose of the sacrament, even if it were a demonstrable truth that more saved people were baptized than weren't. Because there are so many unsaved persons who are baptized! It's entirely possible that in some populations, there are more unsaved-and-baptized persons walking about than there are saved-and-baptized. And nevermind the mode or the timing of the baptism!
Baptism is only a sign, and the teaching that explains the sign, and goes along with the sign, and surrounds the person, and follows the person--THAT, brethren, is what blesses an adult or infant who is properly baptized.
