sir82 - I'm sure facebook would've been glad to do that, if they could get the workforce for free.
I'm not sure how much of a difference the website will make in either direction if they're going along with their current methods. I doubt many are finding the webpage without encountering the literature first (though, this could change if/when the WTS starts buying google ads ala the mormons and scientologists) so they're not really increasing the number of people who are contacted. Since there's a fairly limited set of cirumcstances that make people susceptible to indoctrination by a cult (usually some sort of very emotional event) if they're not already involved via family/friends/whatever, the only way they'll get more people is to broaden the net, which they're not really doing.
Now, if they start buying ads online, that could really change things.
On the other hand, you've now got JWs searching the web for JW.org, and most importantly they're searching for the kingdom ministry since apparently that's not something that should be distributed to the public under any circumstances and can't be put on the public web site. The problem is that people aren't going to wake up until they're ready. I experienced this myself...I'd been getting my KMs from jwleaks and here for months, making sure to loyally avoid reading any information that might be defamatory. I saw stuff about child molestation, but that was easy for me to rationalize away. It wasn't until I'd more or less realized that I'd been lied to (yay for the overlap doctrine!) that I actually started to believe anything that I read online. I'm sure it'll help some (as it did in my case) just because those who stumble upon 'apostate' material will know where to look once they're ready, but I don't think it'll make much difference in getting people to that first step, where they're finally able to accept contrary information.
It's often said here that their greatest weakness is the baggage of their past, and I think that's true when recruitment is concerned. I don't think it's true (or, at least not as true) as far as retention is concerned. The reason I think this is because the truth of the WTS's past is so absolutely absurd that no one who's fully in will accept it if you tell them. The WTS banned organ transplants then backtracked? You're lying, I can't trust anything you say! They used to ban vaccinations? Get out of here you lying appostate! They where a member of the UN? There's no way, its not even worth my time to look it up! The absolute insane level of the hypocricy of the org is almost an advantage, because it sounds so unbelievable, especially if your only picture of the org is the nice people that you go to meetings with. Its not until you find that one thing that hits you in just the right way that all the rest becomes believable.
IMO it may backfire slightly in that people will feel a little safer in leaving once they're ready, but I don't think it'll make a huge difference in getting people to take that first step and open up their mind. That said, its definitely possible that that little push may be enough to create a chain reaction where the absence of a few causes the rest to get curious. This is one of those things that's just insane to try and model and we're just going to get 10000 different pieces of anecdotal evidence that all points in different directions. That doesn't mean it's not fun to talk about, though.