I would recommend using extra fields for downloadable files over the attachment feature.
Extra fields provide more flexible. I use them to the majority of my site (list image, item image, meta data, downloadable files, etc.)
For example, you could use a link type extra field. This way you would be able to control the text, link URL, and target.
Or you could map each element to a seperate extra field providing even more flexibility, as you could add a field for an image, or use a dropdown to standardize the text link (Download PDF, Download File, Access Attachment)
I love extra fields so much, that I am doing a JoomlaDay session about the many ways you can use them to power your Joomla! website:
joomladayflorida.com/sessions/event/30-a-look-at-the-amazing-things-you-can-do-with-extra-fields 
