DDOSing is not worth the trouble you would get yourself in for even suggesting such a thing. When a certain group was in protest of Scientology the Scientology site was DDOSed to the point of crashing, but the people that were doing that were organised in several corners of the internet, had been protecting their identities through various means (Good Luck! I'm behind seven proxies! [its a joke]), and then there was a followup of worldwide protest after there was a ton of attention on the issue in addition to harassing different locations of the church.
I was actually in a lot of the temporary "anon" IRC's during this time and it's not as effective as even those groups like to think unless you have a "more than ready to overreact" type of target. WTS would probably only complain internally for the most part and not try to fight back in the desired way (depending on if you are indeed thinking of mimicking a similar event). Scientologists were targeted specifically because of the ways they react to opposition which I will not go into here.
What you would have to ask yourself if you were planning on doing such a thing is "will anyone give a darn?' and "Will it give them more fodder to cry that they are being persecuted?", which some almost enjoy it seems.
There are other ways to manipulate the internet in your favour, with no legal implications.
I'd give you an accounting of how these things go, sadly for the sake of sharing, most of the archived history of these events are on sites with lots of NSFW and offensive material. I did however find the consequences of the DDoSer's actions with some info on the other tactics that they used (black faxes etc). http://news.softpedia.com/news/Hacker-Charged-for-Cyber-Attacks-Against-the-Church-of-Scientology-96009.shtml
The best way to expose someone, is by telling the truth without exaggeration and showing evidence. It often will speak louder and prevent your target whoever they may be from making themslves a victim. It also saves you fines and jail time.