Hi mcoutos,
CB Subs has the ability to sell 3 things - membership/subscriptions, donations and simple products.
If you are talking selling an event ticket then the product version of a plan can cope with this. I personally would opt for Virtuemart and set up user groups as CB Subs will add new users to the correct shopper group for their plan. Virtuemart allows you to display different prices to different groups provided the user is logged in.
Membership plans can be changed as often as you need. One of my clients has just 3 main plans for registration/upgrade but they have a one time offer on first registration to a special price plan. If it is not taken then that user will not get to see the plan again.
CB Subs can protect all content. My same client allows silver and gold members to access back issues of journals on-line. Bronze members can see the list of journals in DocMan but they cannot access them (a good teaser!)
Support is community based - hence me supplying this answer
Hope this helps.