I'm going to venture a few comments about the paedocommunion debate.
i) From what I can tell, many proponents are affiliated with the Federal Vision. At the same time, I think the case (such as it is) for paedocommunion is logical separable from the Federal Vision.
ii) It's easier to argue for paedocommunion if you already embrace paedobaptism. If, by contrast, you're a Baptist or Anabaptist who espouses credo-baptism, then you can oppose paedocommunion on the same grounds.
I'm not saying paedobaptism entails paedocommunion. But objections to paedocommunion tend to parallel objections to paedobaptism.
iii) On a related note, contemporary Presbyterians typically argue that the children of believers are entitled to the covenant rite of baptism because they are covenant children. If you are a covenant child, then that entitles you to the covenant sign. But that logic plays into paedocommunion.
iv) From what I've read, the stock objection to paedocommunion is that it violates what is required of communicants in 1 Cor 10-11. However, it's tricky for a paedobaptist to make that argument:
a) Baptists typically object to infant baptism on the grounds that all the explicit examples of NT baptism specify adult baptism. Paedobaptists typically counter that this reflects sample selection bias. In the nature of the case, the NT church was dealing with converts to Christianity. A missionary setting. So accounts of NT baptisms naturally select for adult converts. That doesn't preclude infant baptism. Just that underage children aren't converts.
But if we accept that argument, then the same argument can be redeployed in reference to 1 Cor 10-11. The emphasis on faith and self-examination is simply a reflection of sample selection bias. Paul is talking about converts to Christianity. Underage children fall outside the sample group under review.
b) Another difficulty is that paedobaptists typically regard parents or sponsors as proxies for the child, inasmuch as they exercise faith in the child's place. But, of course, that argument is transferable to paedocommunion.
c) A complication with making the communicant's intellectual aptitude a condition of receiving the Lord's supper is the case of the developmentally disabled, or elderly Christians who are going senile.
For instance, one duty of deacons is to bring the Eucharist to shut-ins or nursing home residents who can no longer receive communion in church. But is there a cut-off when dementia reaches the stage where a Christian now lacks the mental competence to make a credible profession of faith?
Of course, it could be argued that if the Eucharist ceases to be meaningful to the communicant, why give it to them? But, then, it's not as if baptism is meaningful to babies.