Add another vote for "no gore." My thinking is people will associate the messenger with the message, so make sure the message is something you don't mind being your reputation. The protesters carrying gory pictures of dismembered babies may be well-meaning people, but even as a pro-lifer I'm likely to say "ew" and avoid them because I think they're interested in gore.
If someone is genuinely interested in going veg*n, they'll probably encounter some gore in their research. Let that be them looking, not the first idea they encounter.
Q: How many poets does it take to change a light bulb? A: 1001...one to change the bulb, 1000 to say it's already been done.