> for example against a dedicated attacker with a botnet Do you have experience with this? My understanding is that there's still trivial work arounds (See chr

> for example against a dedicated attacker with a botnet Do you have experience with this? My understanding is that there's still trivial work arounds (See chrome extension "Buster") or services where you pay to have a human go through it for pennies. If somebody is targeting your site then your captcha will be useless no matter what.