Hi Tobias,
Yes you are right, when you use Rule Tasks now you need to call fireAllRules. The behavior of the Rule Tasks Nodes in the current version works as follow:
The rule task node will activate the ruleflow group that contains your rules. At that point all the activated rules inside that group are elegible to fire. For that reason you need to call fire all rules in order to fire the active rules. I'm trying to change that behavior to call it automatically.
Cheers