I am currently investigating how best to test our OSGi application intended to run on Apache Karaf. The obvious option is Pax Exam with labs-paxexam-karaf (see http://iocanel.blogspot.com/2012/01/advanced-integration-testing-with-pax.html for a tutorial). However, I am concerned about performance (since Pax Exam apparently starts a new framework for every test method). I've also found that Arquillian has some OSGi support, though that isn't its main focus. JUnit4osgi isn't an option, as it only supports JUnit 3.
For someone unfamiliar with either framework, which is better to start with? What are the tradeoffs?