I purchased a set of 3 metal containers (stacking and with a lid) like those in your picture. They turned out to be pretty frustrating to me because of the same issue - the dough balls kept sticking all too easily. I guess more oil could help.
After a couple of bouts of sticking, I starting using cut-out rounds of the non-stick aluminum foil that you can buy on the bottom of the containers. Worked - but too much of a pain and workaround.
Also, being aluminum, I kept getting some black residue when washing.
Long story short, they are in a closet in my garage and they are unlikely to see the light of day again.
Right now, i use these:http://www.pizzamaking.com/forum/index.php/topic,22232.msg230016.html#msg230016
They have a nice little pop-up lid so that there is no gas build-up.