I am not sure that it gives any substantial increase in graphical quality over what you can obtain using the FFXI config utility:
..\Program Files (x86)\PlayOnline\SquareEnix\FINAL FANTASY XI\ToolsUS\FINAL FANTASY XI Config.exe

It is ban-worthy to use programs that interact with FFXI in any way. However, from the same link that Shirai posted:
SQUARE ENIX MAY SUSPEND, TERMINATE, MODIFY, OR DELETE FINAL FANTASY XI SERVICE ACCOUNTS, CHARACTERS, VIRTUAL GOODS, OR THE SERVICE ALTOGETHER, AT ANY TIME FOR ANY REASON OR FOR NO REASON, WITH OR WITHOUT NOTICE OR LIABILITY TO YOU.
Given the variability in enforcement, whether or not it increases your odds of being banned is difficult to say. Everything you do is at your own risk and you do risk your account. However, even just paying for your account is not risk free (especially if your credit card company does automated chargebacks).