People who are willing to put their life on the line for 2-3 washer in their suspension is stupid if you ask me.
People is stupid huh??
The washer method is perfectly safe IMO for a 2"drop. I have used this method on my car for the past 12 months with no problems whatsoever. My mechanic, whom I completely trust, (asa certified and ****) said he uses this trick on cars that don't have adjustable rear cambers all the time.
BUT if you are slamming your car (i.e. 3-4 inches) you have to use a lot of washers and this will lead to a lot more stress on the bolt. In that case, I would buy a rear camber kit.
Also, if you end up needing more that 2-3 washers, I would buy a slightly longer grade 8 bolt just to make sure it is well seated into the frame.