My experience with payment gateways (note: I have not tried the new subscription services: Chargify, Spreedly, etc) was that their recurring billing support was

My experience with payment gateways (note: I have not tried the new subscription services: Chargify, Spreedly, etc) was that their recurring billing support was rather inflexible. We had to implement it ourselves to get the customer experience we wanted (30 day free trials, that kind of stuff). So this may be less of a downside than you suppose.