Just ran into a situation where I don't want to display a read more link for two specific articles. With Smarty I have excluded the bit of article html and made it $F2C_ID dependent.

So: If the F2C ID is NOT 4 or 6, the read more link will be visible.

{if $F2C_ID !=='4' && $F2C_ID !=='6'}
<a href="/{$JOOMLA_ARTICLE_LINK_SEF}" target="_parent"> ... read on
{/if}

Hope it can be useful for you too!