You don't have to be a PCLP to upgrade to ND6. And whether or not this is worthwhile is up to you. You don't say whether you are an application developer or system administrator, so I suggest you check out the ND6 update page at http://www.lotus.com/certification. Then select "Notes Domino 6 Update Exams Now Available" from the Highlights section of the page.
This was first published in February 2003