The author of the bottom code states that he uses the_excerpt_rss() because it "strips out all formatting tags". My question is do both codes below "strip out all formatting tags" ? What is the difference between the two codes below? Which would you suggest using?
<meta name="description" content="<?php echo strip_tags(get_the_excerpt($post->ID)); ?>" />
versus
<meta name="description" content="<?php the_excerpt_rss(); ?>" />
By default, the_excerpt_rss() does not strip HTML tags, parses out links for numbered URL footnotes. In order for it to actually strip tags, you will have to pass 2 to the parameter $encode_html (see http://codex.wordpress.org/Template_Tags/the_excerpt_rss):
$encode_html
(integer) Defines html tag filtering and special character (e.g. '&') encoding. Options are:
0 - (Default) Parses out links for numbered "url footnotes".
1 - Filters through the PHP function htmlspecialchars(), but also sets cut to 0, so is not recommended > when using the cut parameter.
2 - Strips html tags, and replaces '&' with HTML entity equivalent (&). This is the default when > using the cut parameter.
I would probably rely on the PHP strip_tags() anyway just because the_excerpt_rss() is intended for use in RSS feeds, so strip_tags() seems cleaner to me.