Great question – the choice to use poles mainly depends on what your sport requires. Are you training for skimo? If so, i would definitely advocate the poles, as they help regulate foot cadence and apply a small load to the arms throughout, not to mention it looks more like skiing than without them.
Similarly, when you think about the bounding motion, the more you can make it look like an explosive version of your sport, the better. In the case of skimo or even running, using a bounding technique wherein you have a very high force application in a short ground contact period is best.
Hope that helps,