I really think it would be much better to have three seperate symbols that appear next to the items name. Even better have no symbol for common items one for uncommon items and a different one for rare items. I liked the rare/ex symbols and don't think it will be as noticable with just a colour.

Also I noticed on another thread someone mentioned that the items name being coloured depending on rarity is totally useless to people who are colour blind, however a symbol would be recognisable by all.