You're suggesting that users use better passwords on sites with no password restrictions. I'm going to doubt that's true and presuming you have no data say that it's likely far from true.
Nope, I said stupid password restrictions. A good password restriction would be one that only measures the entropy. The idea that we should use no more than 8 letters, alphanumeric with symbols is stupid and demonstrates ignorance with how hashing works.
On the other hand, everybody knows they have to make up bullshit passwords to pass arbitrary restrictions, so they may never try an easy to remember but good password on the few sites that don't.
http://security.stackexchange.com/questions/33470/what-techn...