I am building a new site based off old PHP site . The registration process uses stages to get all the necessary info from the user. I do not know PHP well yet, and want to do this with Joomla. It's subscription based service (physical not virtual) and the user would not want to have to load a cart every week but be able to change preferences. I have looked at Joobi stuff, JSubscription, JCommunity, and their others. I have Community Builder installed and VirtueMart, consider purchase of CBSubs?. Lastly I notice RT promotes JomSocial. Overall I do not know which configuration will work the best (considering RocketTheme??) and fulfill my needs.
Honestly, I do not have a good answer for you. I have not used any of those except for Virtuemart. I will move this post out to the General Forum where it will be seen by the masses and hopefully you will get a good response that is a bit more intuitive than mine.