Waveline DC6000 here. No complaints. I like the fact that it's adjustable and has the slow start.....although my first water change reminded me of the slow start. I typically pump new salterwater into my partially emptied sump on a water change. When the water approaches the top of the sump, I'd turn on the return pump. With the slow start, I had to quickly unplug the pump pumping in new saltwater. Now I turn the return pump on first and then start the pump for new water.....timing is about right when the return pump comes on and the sump is almost full.
As far as noise, I don't hear the Waveline at all, over the whine of an MP40 on the way out, and the fans on my LED's. FYI, it's dead silent.