First thing. #2) If you’re changing the BP template pack files, then backup and remove the header-buddypress.php and sidebar-buddypress.php files we created from your quickstart theme folder in server.
It’s either the 1st method (changing BP template pack files which you did) OR the 2nd method (xxx-buddypress.php files), because mixing them for BP Compatibility is unnecessary and can cause issues if you mix up your HTML structure.
#1) If you delete the header-buddypress.php and sidebar-buddypress.php files then the changes to the stylesheet will be different assuming you got the markup correct.
Before taking final measures however, perhaps you’d copy source code of your full width page template from quickstart and post to pastebin.com. We could take a look at changing header- and sidebar-buddypress.php instead if feasible.
