Ask HN: Payment Gateways?

Reading up on the Chargify pricing increase (http://news.ycombinator.com/item?id=1780348 and http://news.ycombinator.com/item?id=1781156) led me to compare subscription payment services, which quickly lead to questions about gateways and merchant accounts:

1. How do payment processors like Speedly and Chargify relate to merchant accounts and payment gateways? 2. Are there any other pieces of the puzzle of getting the money from my paying, online customer to my account? 3. What should one look for in a payment gateway and/or merchant account? Does one need multiple gateways and/or merchant accounts? 4. Any recommendations for payment gateways and/or merchant accounts? 5. Any reasons not to go with PayPal instead? 6. Any one have experiences with Braintree?

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From my notes: Brief comparison online subscription payment processing options October 2010

    *   CheddarGetter (https://cheddargetter.com/)
          o Up to 20 customers free
          o $39/month for up to 1000 customers
          o $169/month for up to 10,000
          o $549/month for up to 50,000
          o requires merchant account
    * Recurly (http://recurly.com/)
          o $29-$699/month plans
          o +20-8 cents per transaction
          o +2-8 cents per user
          o must pay gateway and merchant fees separately
    * Spreedly (http://spreedly.com/)
          o $19 per month + 20¢ per payment transaction or 2% per payment transaction, whichever is less
          o Payment gateway required
          o 5000+ transactions per month, ask for bulk pricing
    * Chargify (http://chargify.com/0
          o  free development
          o $99/month for up to 500 customers
          o $349/month for up to 2000
          o $999/month for up to 10,000
          o branded payment pages
          o set up your own merchant accounts separately
    * Braintree (http://braintreepaymentsolutions.com/)
          o includes merchant account
          o payment processing with recurring payment add on option
          o 2.89% + 30 cents/transaction
          o $15/chargeback
          o $75 monthly minimum
          o one time $99 setup fee
          o $20 + 1 cent/card/month for credit card info storage
          o 20 cents/subscription per month for recurring payments