They may not keep minors out or whatever but they do give you a chance to sell to the surfer before they hit the free stuff. I think once they hit the free content your chances of selling to them go down quite a bit.
How a warning page effects search engine listings these days I dont know but I think youre right about it not doing well with the search engines. And Im not a lawyer but I dont think it would protect you from being prosecuted for any kind of obsenity charges.
Hell... I may remove mine too
