It would seem to me that if the users can pick the style sheet they want to use, they should also be able to pick an icons stylesheet. Some of the forum "pros" may like the non text icons for posting, back, next etc. However the board default should be an icon set with the text in it so that a newbie can figure out what they mean. In addition an option should be to only use straight ascii text instead of the icons.
On one of my forums, I cannot use wwwthreads because the icons increase my "hits" so much my provider shuts me down.
Kirk