I contacted Linode about this, since one of my Linodes has an annual discount applied (https://blog.linode.com/2008/07/31/referral-system-annual-discounts/ http

I contacted Linode about this, since one of my Linodes has an annual discount applied (https://blog.linode.com/2008/07/31/referral-system-annual-discounts/ https://blog.linode.com/2008/07/31/referral-system-annual-di...) and I was not sure how switching would affect it. They responded: "Unfortunately, at this time if you have any Linodes that you pay for annually or biennially, enrolling in the metered billing beta will remove your discount, and the process of changing over cannot be reversed."