No and No
I think it would be benefical to let the smaller countries in the UN. It's not nesscacarely giving them a bigger voice. But just letting them give their opinon in some of the United Nations key subjects.
The United Nations requires the support of the most powerful nations on Earth to retain legitimacy and whatever power it has. Bigger nations would be more apt to support the organization if they are given more say (as in the Security Council). Secondly, it just isn't fair to give smaller nations a larger say proportionally than larger nations who, in the grand scheme of things, actually dictate world events.