I have seen neither the forklift thing nor the webcomic that have been discussed, though I have followed the conversation since the beginning and I have to say that I'm impressed with how mature it has become. Ending every post with "I really love you, so don't take my comments the wrong way" may seem overly cautious, but it has helped clear the air and kept things very friendly.
Now that the conversation has veered into an area that interests me, I feel the need to comment on the idea of intent and sadism. I don't think anyone could call an audience sadistic for laughing at something funny, but I do beleive that there is a level of sadism in portraying gory dismemberment as funny. No matter how fake it is, a guy getting cut in half is a very bad thing--by showing it in a fake, over-the-top, comic way the makers of the film have essentially tricked you into laughing at something terrible. That is sadistic not because of what it shows or how it shows it, but because of the unnatural reaction it has created in the viewer.
There was a brilliant skit on the old Hugh and Laurie show that played with this same concept: they talked about genital herpes, but in such an outlandish context that the audience couldn't help but laugh. Then the actors broke character and challenged the audience, accusing them of being cruel and insensitive about a very serious subject, but the subtle way in which they did it was so meticulously funny that the audience just kept laughing despite feeling guilty about it.