Some observations:
This style of filmmaking is usually (somewhat misleadingly) called cinema verite. (accents over the 'e's in that). It isn't really because it's fiction, but that's the style they're shooting for.
I personally am glad that PA is doing well. I may or may not see it, since it really attacks a vulnerability of mine, but it deserves to succeed because if nothing else it was a little different and well-executed.
Re: Saw. I saw the first one; it was clever, inventive, and original-- to the point where I was prepared to endure the gore; it had a pretty specific point. However, there are too many films that indulge in gore for gore's sake, and the Saw series seems to have devolved into exactly that, perhaps in an effort to attract that audience.
I have my reasons for not liking gore. Foremost among them is that I think to almost every filmmaker, it becomes more about trying to be revolting rather than horrifying. (To wit: Midnight Meat Train.) I will
always think that the suggested is more powerful (not to mention artful) than the explicit-- my mind is a very strange place, and my imagination is very creative: it's highly likely I'll come up with something wayyyy scarier and disturbing than what you could show me. Additionally, you allow each person to scare themselves rather than having to come up with something that will scare many, many people, and even then, you're sure to fail with some.
EDIT: forgot to include the pithy link applicable the "Saw" series:
http://www.penny-arcade.com/comic/2002/12/13/