Having tested and explored various components for the Joomla CMS, we (btforex.com) ended up every time at the JoomSuite programmers. Registration and membership stability and security is of high importance to us, whiich is amply given by the programmers here at JoomSuite.
The speed of service has been simply excellent. The few issues we had were quickly solved and our emails were almost instantly replied to.
On a critical note, we would prefer the payment plugins to come from Joomsuite themselves rather than a third party publisher.