i disagree on those last to statements - refresh.
About the 'add more darker colors,do you really think it will blend? i mean. Look at the render and your saying add like black or darker colors.
The text is text, it aint the main point. i mean it aint bad and the signatures size is ok but above 600x200 is terrible.. i personally use sizes such as 500x150, 400x150, 400x200.