In my opinion one is as futile as the other.
If a well-funded professional investigation such as Operation Grange cannot come up with the goods, what chance has an amateur enterprise got ?
I disagree jassi. We all know that many people in Portugal view their police force with some trepidation given the past so in my view a civilian exercise might just get that little bit further. I certainly feel that every avenue should be explored in the search for Madeleine, something which has sadly been lacking in the last few years.
There is every possibility that someone somewhere knows more than they are letting on so appealing to their better nature might just achieve some success. The other thing about a civilian initiative is that guarantees of anonymity can be given to informers for their protection against press intrusion.
IMO the police will never solve this case by knocking on doors and hauling people in for interviews. This case will only be solved if someone freely comes forward with credible information.