i personally feel that signature campaign here will only create the brand awareness. But won't given any conversion. Because most of the people in this forum are active here only to carry the signatures and make money.
It is not worth it after all, signature campaigns are just a way to expose your project, but just using your signature for more than one month or so, is a waste of time and money for the bussiness owner.
You need to spend a lot of money in order to pay them out too.