The BT movement (or Chozrim Bitshuva) has a few thousand people who were attracted to it. Rick has some documentation about an overview about it on the Chabad/Lubavitch page and on the Ultra-Orthodox page.
Many times people forsake their families and friends when they become BTs. I found, that, especially in the case of Chabad BT's, it's impossible to stay friends with these people unless you go along with their beliefs or give them tzedakah money.
Chabad, in particular, goes after wealthy people and are successful many times in getting these people to donate.
The Chabad center in Basking Ridge, NJ is expanding and the movement attracts people from non-orthodox backgrounds.
I find this a worrisome trend, especially with what's happened within Chabad after the death of the last Rebbe and the "messianist" movements within Chabad. Someone on the yahoo group Moshiach Talk, claimed that the Rebbe never actually died.
The BT movement goes after young people in particular and immigrants from other countries who have minimal religious training or perhaps none at all like the Jews from the Soviet Bloc.
It's easy to convert people who've had no experience being Jewish religiously and who don't know how difficult it is to be an orthodox Jew. Not to mention the resistance you can get from non-Jews over it.

The funny thing thing is that the whole time before I converted to Christianity, and I was still within the Jewish faith, I never saw any orthodox Jewish people, let alone outreach workers, around the area. Even when I was being persecuted in school for being Jewish.
Then, when I converted, all of a sudden there were Jewish religious leaders all around me. Only after I became a problem to them.
One yeshiva student, not knowing my background, (these guys like to pontificate and they think they know everything), told me, "before you left Judaism, you should have checked out what it had for you."
Really? I had relatives who were orthodox, they didn't do anything for me. And I don't know if my Hebrew school teachers knew what was happening to me in public school, but they didn't do anything about that either.
I tried to join Jewish groups, like the Young Judea, but when I got to one YJ meeting I got threatened by someone who had an advanced rank in Karate.

In "An Overview of the Baal Teshuva Movement" it was written that it really isn't a good idea to let your children experience what these rabbis have to offer. Let me add to that and elaborate my views now.
Firstly, don't expect these rabbis and haredim to have any respect for your religious beliefs unless you're orthodox yourself.
And "honor your father and mother" in the Decalogue only applies to orthodox parents because "first the parents have to honor God and then the children can honor the parents".
These people believe that only their version of Judaism is valid and that all other forms watered-down, or perhaps more accurately, counterfeit.
These people believe that your children are in dire need of being straightened out and luckily they came to Israel where they can be retrained (one worker actually told someone studying at Aish that he was "reprogramming" him) in the "proper path".
I heard someone complain that these rabbis hate everyone who isn't exactly like them. I'm not sure if that's the case or if I'd go that far, but I know that they have no regard for any religion save Judaism and at that "Torah True Judaism".
One should be very wary that a child sent to Israel might not come back or might come back to completely upset the family's balance.
In my family, we had problems because my folk's tended to lean towards orthodoxy and my take on it was that they were being somewhat hypocritical. A lot of Hebrew Christians have that comment about their parents too.
I worked out what I believe and my belief and practice are consistent. If your child or a relative become a BT you'll probably have to fight over doctrine.
If you don't believe in miracles, tell them so. Whatever form of Judaism you practice, Conservative, Reform, etc, you should be aware of what these branches of Judaism believe. And you should tell your family what and why you believe, because oftentimes the schools don't.
I went to a Conservative Hebrew school and not once (and I was an "A" student) did we even discuss what separated us from the Orthodoxy or the Reform.

BT as a phenomenon is relatively recent. In times past, the orthodoxy seemed to want to have little to do with non-orthodox and didn't woo them to orthodoxy. Years ago. Shlomo Carlebach told a prominent rabbi that "we need new yeshivas .... because there are thousands of people on their way back..." The rabbi told Shlomo, "I've never seen a comedian like you before."
Shlomo also said that those who have "a big mouth about teshuva now [should stop talking] because they're the ones who made the live of the first BTs miserable." He also said, that he overheard someone say that "because of us (the fruma people, there's a BT movement." Shlomo told the person that "despite of you there's a BT movement."

GW was another outreach worker. He also authored a few books on Judaism. But last I heard he "cut the plants" a la "Acher" and became estranged from orthodoxy himself. Seems he skipped out on his wife etc.
I knew him from a Jewish cafe house that my parents helped set up on LI. The cafe house purpose was to allow young Jewish singles to meet and also to combat Hickman's cult which was in the vicinity.
One time, I tried to engage him in a conversation and I made a comment, "If someone reached into your head with a Mix Master it would change your soul". He said something about, "... and apikorsus (heretic) like you..."
Well, the Hindus believe that there's a part of the soul called the "Atman" which doesn't change and they disagree with the Buddhists who call a component the "Anatman" which does. I think comparitive religion is wonderful, don't you? GW didn't.