I took a look at your website, and it's unlikely that it will get many negative comments because it's in an un-competitive niche compared to something like hotels -- where 100 or more businesses in one city may be furiously and unethically competing for a limited number of customers.
In industries like hotels, I guarantee that competitors will regularly be posting subtly negative comments on each other's websites. (As soon as they learn what Sidewiki is.)
Just like with Google Maps, it will be impossible to get issues resolved in any reasonable length of time. Google will not invest resources in a customer service team large enough to deal with Sidewiki.
My main complaint against Sidewiki is about hijacking of content and users, but vandalism of websites is also an issue in some competitive industries (like hotels).