qaf-cucumber can be used for one of the following cases:

1. If you want to use cucumber runner instead of TestNG (standard cucumber runner)
2. If you want to use cucumber step implementation with TestNG runner (BDDTestFactory2)
3. If you want to use both cucumber and TestNG together (CucumberScenarioFactory)

In either case You can use all the features of QAF along with BDD2 and step implementation can be either of qaf steps or cucumber steps.