1- Greatjoomla website represents great range of extensions but they create huge amounts conflicts if you do have a complex website.
2- About petition extension, my only concern is that a logged in user can change his email address (when signing a petition) and re-sign. In fact, a registered user can register thousends of times just by writing fake emails. I have mentioned to develope but no results on adding (at least as an option) so that
first only registered user could sign a petition
second a registered user could sign the petition only once.