I was experiencing problems with switching currencies while in product listing.
& was still there, included fix did not work for me.
So I made a little adjustment using bchecketts fix.

If You are experiencing this problem find in seo.class.php

$params = ( sizeof($params) > 1 ? implode('&', $params) : $params[0] );
$url = $this->href_link($this->uri_parsed['path'], $params, 'NONSSL', false);

After this add:
# BC Redirects shouldn't have '&'s in them
$url = preg_replace('/&/','&',$url);

And delete this two lines from the bottom of file.


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