Trying to do utilitarian math around pain caused by existence gets weird though because non-birth also precludes the possibility of joy and happiness so isn't it 'immoral' to not have as many kids as possible by the same lost/prevented potential logic?
As you alluded to, which action is moral depends on the framework you subscribe to. The most direct contra-framework to the utilitarian approach is negative utilitarianism - challenging whether the goal ought to be to maximize pleasure or to minimize pain as a priority.
If you maximize pleasure as a first priority, you can either say that "As long as human life is in general good, I should make the choice to create one" or "As long as a human life produces any good, I should make the choice to create one".
This gets into an interesting sub-point with respect to animal experiments - most people would argue that animal experiments produce some good (Advances in human health). Moral critiques of animal experiments, thus, can rely on either "Hurting animals is bad" (Negative utilitarianism, more or less) or "The pain we create does not outweigh the value they produce". The later point is particularly poignant because the species experiencing the pain does not receive benefits of the pain (Thus there's no "community sacrifice").
I think anything that tries to optimize a single metric just leads to silly conclusions. Like if we minimize pain including potential future pain killing everyone can be 'scored' as 'moral' since it cuts off all future pain.
