My favorite thing about this is how it exposes non-scientists to the first (and IMHO most exciting and least appreciated) phase of research - thinking up experiments.
It also exposes your research plan to other scientists when your work is at a stage where it's the easiest to be scooped. I have a science project idea to be crowdfunded, but I'm still a bit skeptical...
That's a real risk. But the longer I'm in science, the more I believe that "ideas are cheap, follow-through is everything." If I'm scooped, it's not because someone else had the same idea (probably lots of people had that same idea); it's because I didn't reduce it to practice first. If getting funding from Petridish helps you reduce your idea to practice first, maybe it's worth the risk of getting scooped.
Good luck! I'm glad more people like you (VC's) are stepping into the game. And in fact, this is going to require a lot of hands on experience. By the way, have you been a researcher before?