Request 1: Make a coupon apply to all of the payments instead of just the first month. Possibly have an option to choose lifetime or the first month.
Request 2: Bulk upgrades, offer a monthly recurring fee; as well as the current yearly fee. Members on Prosites are accustomed to month to month fees.
Request 3: Premium Support: Allow for this page to be customized, like the checkout page. Having the ability to add content above the form or even to have the ability to embed code from a 3rd party service would be great as well.