Question related to some earlier posts:
What about a childfree person who is trying to decide whether or not they would like to have children, we are actively discussing this decision, having been brought up by them. They bring up the issue of, "But kids are loud/annoying/messy and I don't know if I would be able to put up with it."
Can I then bring out, "But you'll love them when they're your own"? Because I think that it's quite true in this situation.
My two cents about that type of a situation:
During a friendly discussion about having kids, I might suggest, "That's true. Plenty of kids are all those things at least some of the time. But, there's the expression "You love them when they're your own" and that definitely holds true for me."
If you're having a discussion that both sides are happily participating in, then it's not so much whether or not it's right for the childfree couple to have or not have kids, and not a judgement on those who are deciding... it's gauging the difference between the two situations, and exploring the good and not-so-good to make an informed decision.
It's like asking (on a much more life-altering scale), "Hmm... which college should I go to?" You can get the opinions of people who have gone to two different universities and then decide. In those cases, I don't think throwing out, "Yes, kids are a lot of work, but I wouldn't change a thing" or "Here's my experience" answers are out of the question.
If during a discussion they want to know the truth, tell them the truth as you feel comfortable telling it. (In a non-"you'll regret not having kids" way.)