Adding a class to the After Excerpt link would make that link much easier to style.
Line 411 in the adv-most-recent.php file could be changed from
if ($afterexcerptlink) $afterexcerpt_html = '<a href="' . get_permalink($post->ID) . '">' . $afterexcerpt . '</a>';
to
if ($afterexcerptlink) $afterexcerpt_html = '<a class="afterexcerpt" href="' . get_permalink($post->ID) . '">' . $afterexcerpt . '</a>';
Also when a span is added to the After Excerpt link the plugin isn't saving it correctly.
For example, when I put <span class="readmore">Read More</span> in there the plugin will display the link correctly on the front side of the site. But it only saves <span class= in the After Excerpt field.
That means the full span code must be pasted in the field every time the widget is saved or the link text disappears.
http://wordpress.org/extend/plugins/advanced-most-recent-posts/