no consensus here

It's a big debate here as to whether it's moral or not to have sex with little girls, with a large amount of confusion caused by the fact that the vast majority of harm is usually caused by society -- imprisoning and shunning the adult, invasively inspecting the girl, and telling the girl that her friend was evil and didn't like her and was abusing her.
Most of us agree that no significant physical or mental harm is done from sexual acts themselves, except perhaps penetration of a child under 7 or so. I think we all agree that oral or manual stimulation most likely won't lead to physical harm. The benefits you mention I agree with, although 'second base' is ambiguous. Realistically, these benefits are pretty minor compared to the legal/social risks they have to be weighed against. And it's foolhardy to not weigh those risks.