I don't have any initial answers for you, but a few questions/suggestions based on the available information.
- What do the operation definitions look like?
- Does the outcome change if you change the order of execution of the tasks in your challenge schedule?
- To remove the "noise" of having very high latency measurements can you remove or drastically lower your target-throughput? See the docs for an explanation of why those numbers (latency, service time) are so different from one another in the current mode for the same operation
- Can you elaborate on in what way specifically JMeter's results were opposite to Rally?
Thanks,
Rick B