K&N vs. UNI

I have been told if you are ridin in dusty conditions do not use the K&N they let micro dirt particles through have seen motors run with the K&N and looking at the cylinder the scratches on the cylinder wall, will not ever run one again, I like my UNI very much when i tore my motor down last time no scraches in the cylinder, I have a K&N with the Alum adpter ring for the 450R it was a $120 when i bought it and know it just sits on the shelf will not use will sell for $50 shipped if anyone wants it.