From what I understand it doesn't take enough out to disturb the cycle though in your question you mentioned nitrates which is the end of the cycle so it wouldn't matter anyway as that is what water changes are meant to lower.
I have chatted with a few people on dif forums and those that use it are quite happy with it's results and no ill efects to fish or cycle.
Side note I haven't gone as far to try it myself yet but am planning to on my next Cannister clean.