Can you say, coolest fucking parent ever? I wish my parents let me do stuff like that when I was that little. One of my goals as a parent is not only to watch out for my kids, instill good morals, etc., but also to be able to take a little risk sometimes and do fun things together. The pride you'll have at the end will outweigh the risk I think. It's a way to share what you love with your kids -- I love riding on both my bikes, road or mountain, and it's important to share that with the kids. I love snowboarding, and I'd like to share that too. Plus, the only way they'll find out what they like and don't like is to try it; so why not think outside the box a bit and do something other than the usual stuff?!
Also, on a side note... I still haven't found a mountain close to me where I can take my bike up on a lift and do this. Sad face.