I have a victron charge controller on a micro hydro setup. The MPPT sweeps are very noticeable, and reduce the output by up to half during the sweeps. They seem to happen quite often. Consistently goes from 30-35V (where it normally sits) up to 60-65v generating half the watts. (no load on the generator is about 72v). The optimum power is never above 40v, so sweeping past that just serves no purpose, and it never seems to learn that :)
I would love to be able to either a) reduce the sweep frequency, or b) limit the upper voltage limit of the sweep.