HN user
CheddarGetter does not require a merchant account or gateway while kicking the tires or while you are in the development or testing phase. You will need a merchant account and gateway before you accept real money but the two processes can run concurrently.
If I'm not mistaken, the kickstart is a limited offer and costs you $699 up front. That's difficult to swallow for most bootstrapped startups.
Spreedly has a per-transaction percentage charge on top of all the other per-transaction fees you pay to the gateway/bank/etc. Not a great option long-term. http://cheddargetter.com and http://chargify.com are much better options. CheddarGetter is a very robust service with usage tracking, branded email communication and microbilling features. Chargify includes a drop-in generic interface like Spreedly.
CheddarGetter does much more than recurring billing: branded fully customizable email communication, transaction error management automation, usage tracking, overage charges, microbilling, analytics. Free to try. No merchant account required during development.