WebForm Database - Is is robust enough for a Petitions site?

Hello everybody:
I need to develop Petitions pages where users can sign on a petition. The webform seems to be a useful input method. Is is robust enough for few hundred thousand entries? How multiple petitions need to be treated? The data seems to be saved in a single array ? (Is it true?).

My requirements are to allow anonymous users to sign on a Petition and view a list of Petitioner's who have already signed on. WebForm_Report modules seems to be similar to Results in web form. If I DO NOT allow anonymous users to "access WebForm results" in WebForm (which allows download) then access to WebForm report is also DENIED.

Any suggestion on how tackle the database and report access problem? Is a solution other than webForm & WebForm_Report? Thanks in advance.