I have Rena filstars on all my tanks. (This makes swapping around filters, if needed, easy as many of the parts are interchangeable. I just went through a bout of leaking with the XP2, but that is fixed now.
Like Christople said, I can barely hear them running. I do not know if there is such a thing as over filtration but, the more baskets (the number of the filstar correlates to the number of individual media baskets) the more flexibility you have to modify the filter media to suit your individual needs.