There is one side effect of using this custom bbcode. Since the application doesn't see a regular 'attach' code for the item, it shows an 'Attached Files' box when viewing the full article in CMS. However, If you have 'Display Full Article in Section Page' = Yes and are viewing the page at the section level, you don't see the 'Attached Files' box. In the example below, the first attachment is using the standard 'attach' bbcode, while the second uses the custom one. For my purposes, this shouldn't be a problem.
Attachment 110858
Attachment 110859