regarding the size issue of coins:
we got rid of $1 and $2 notes as well. It's rare to mix up a ten cent piece and a $1 coin. Originally the 50 cent coin got confused with the 20 cent coin so the changed its shape. The two dollar coin is twice as thick as the 5 cent one. It seems to work pretty well over here.
Addressing the "Urban Myth" that the copper 1 and 2 cent coins were uneconomical. Apparently no one circulated them. People emptied their pockets at night and and only grabed the larger coins on the way out. When I read that I smiled and thought of the giant jar of 1 and 2 cent coins that was on the shelf which I still have like everyone else I know.