I have not attended any Front Sight classes, but if I had the means I would. From everything I have seen and heard about the training, it is top notch.
I am on the Front Sight mailing list and I get all of Piazza's promotions. My take is that he has more than his share of P. T. Barnum in him. He very aggressively markets his product. He also gives many training classes away in his promotions. Like buy one, get 5 free for Church members who are becoming the security force for their church. Of course, recent church shootings are used in the promotion.
I have also heard about the lawsuits. I have researched them to some extent and have heard all of his side of it through his mailings. I am leaning a bit in Piazza's favor on this, but am not positive his was not at fault.
If he is sincere in what he is trying to accomplish but has not been able to due to legal/financial obstacles, he is not a snake, just not as good at this as he advertised he was.
It has been reported that he is a Christian Scientist and I have not found any proof either way, except he does portray the aggressive approach often associated with that belief.
Front Sight has a series of videos called the Front Sight Challenge in which four competitors participate with a particular firearm type: pistol, rifle, sub-gun etc. Two of the participants are Front Site students and two are from the military or police ranks.
If you want to observe the result of the training, visit the site and sign up for the series. Unless you want to be on his mailing list, make a new Hot Mail or GMail account for this purpose.
I have not stopped the mailings because in addition to the never ending sales pitch I think he does present some good information.
I am not a Piazza fan, but am interested in the product.