I have a dcp-5000 running for over 1.5 years, no issue whatsoever. Before this I had a dcs pump, which runs with a high pitched whine.
I think mechanically, this pump design is mature/stable. I think there is a newer version that has added features to the controller only, like running it like a wavemaker. good for use in closed loop. I can do the same when I clean the pump and hook it up to RN-1 controller. The pump does the random, pulse and wave modes, but does not do the reverse mode.